
Class ft (i* 



- 



Book. 







Copyright^ . 



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COPYRIGHT DEPOSIT. 



PATHOLOGICAL 
TECHNIQUE 

A Practical Manual for Workers in 
Pathological Histology and Bacteriology 

=^=^^==^ including z=zzrznzn^^=rz^ 
Directions for the Performance of Autopsies and 
for Clinical Diagnosis by Laboratory Methods 



BY 

FRANK BURR MALLORY, A,M,, M.D. 

Associate Professor of Pathology, Harvard University Medical School; 

First Assistant Visiting Pathologist to the Boston City Hospital j 

Pathologist to the Children's Hospital 



AND 

JAMES HOMER WRIGHT, A.M., M.D. 

Director of the Clinico-Pathological Laboratory of the Massachusetts 

General Hospital ; Instructor in Pathology, Harvard 

University Medical School 



Third Edition 
Revised and Enlarged 
With 156 Illustrations 



PHILADELPHIA 

W. B, SAUNDERS & COMPANY 
New York J904 London 



LIBRARY of CONGRESS 
Two Cooies Received 

AUG 18 1904 
(^ Oooyrfsrht Entrv 

CLASS o- XXo. No. 

' COPY B I 



■■' 






n 



Q 



Set up, electrotyped, printed, and copyrighted. October, 1897. Reprinted, 

September, 1898. Revised, reprinted, and recopyrighted, July, 1901. 

Revised, reprinted, and recopyrighted, July, 1904. 

Copyright, 1904, by W. B. Saunders & Company. 



Registered at Stationers' Hall, London, England. 



ELECTROTYPED BY 
fESTCOTT &. THOMSON, PHILADA. 



PRESS OF 
W. B. SAUNDERS & COMPANY. 



TO 

HENRY F. SEARS, A.M., M. D., 

WHO BY HIS LIBERALITY FIRST RENDERED POSSIBLE PATHOLOG- 
ICAL RESEARCH IN BOSTON, AND BY HIS PERSONAL 
WORK ADVANCED AND STIMULATED IT, 

THIS BOOK IS RESPECTFULLY DEDICATED BY 

THE AUTHORS 



PREFACE TO THE THIRD EDITION. 



The book has been thoroughly revised for this, the third 
edition. We have cut out whatever seemed antiquated or 
unpractical, and we have added much new matter, chiefly to 
Parts II. and III. 

Among many additions to Part II. are : Hill's Hanging 
Block Method ; Harris' Celloidin Sac Method ; Methods for 
the Isolation of Typhoid Bacilli from the Feces ; and sec- 
tions on the Bacilli of Dysentery and of Chancroid, contain- 
ing certain improvements in the methods of their isolation. 

To Part III. the most important additions are : Improved 
methods for imbedding and manipulating frozen sections by 
Wright, not published before ; the latest staining methods 
of Weigert; Wright's Blood Stain, and directions for its 
application to Blood Films and Malarial Parasites ; the 
methods of Cytodiagnosis and Inoscopy in the exami- 
nation of serous fluids; Benda's Stains for Neuroglia and 
Myoglia Fibrils and for Fatty Acid Crystals ; Mallory's 
Stain for Fibroglia Fibrils ; Best's Carmine Stain for Gly- 
cogen ; and Mayer's Stain for Amyloid. 

Some new photographs have been added, which nave 
been made by Mr. L. S. Brown, of the Clinico-Pathological 
Laboratory of the Massachusetts General Hospital. Among 
these we call special attention to those of malarial parasites. 

Boston, July, 1904. 



PREFACE TO THE FIRST EDITION. 



This book is designed especially for practical use in 
pathological laboratories, both as a guide to beginners and 
as a source of reference for the advanced. We believe that 
the book will also meet the wants of practitioners who have 
more or less opportunity to do general pathological work. 

Every autopsy presents for solution a problem which may 
be simple or complex. The known quantities are certain 
clinical symptoms and physical signs ; the unknown quan- 
tities are not only the gross and microscopic lesions that 
may or may not have given rise to the symptoms and signs, 
but also the etiology of the lesions and the order of their 
sequence. The solution of the problem often requires the 
highest skill in post-mortem, bacteriological, and histo- 
logical technique, but in its solution lies the fascination of 
pathological work. 

It has seemed advisable to us to present, so far as possible, 
a consecutive statement of the methods employed in solving 
the various problems that arise, so as to avoid the repetitions 
that necessarily occur when the three usual divisions of the 
subject are separately considered by different writers. It 
is hoped that, this method of presenting the subject will 
bring the student to the realization that the mechanical per- 
formance of a post-mortem examination and the inspection 
of the gross lesions constitute usually only the beginning 

of the solution of the problem, which should be investigated 

11 



12 PREFACE. 

bacteriologically, histologically, and chemically as far as our 
present knowledge will permit. 

We should particularly advise the routine bacteriological 
and histological examination of the more important organs 
in all suitable cases. Naturally, the autopsies in which the 
lesions are due to a single etiological factor are the most 
valuable and instructive for a clear understanding of the 
pathological processes present. 

Besides the methods of post-mortem examinations and 
of bacteriological and histological investigations connected 
with autopsies, we have added the special methods em- 
ployed in clinical bacteriology and pathology. 

In the parts devoted to Bacteriology and to Pathological 
Histology we have not endeavored to make an exhaustive 
collection of methods and formulae, but rather to select 
those which have been found of the greatest service in 
practical work. 



CONTENTS 



PART I. 

POST-MORTEM EXAMINATIONS, 

Introduction, 17. — Instruments, 18. — General Rules, 21. — Suggestions to 
Beginners, 23. — Private Autopsies, 24. 

I. EXTERNAL EXAMINATION OF THE BODY. 

Inspection of the Body as a Whole, 26. — Special Inspection of the Different 
Parts of the Body, 27. 

II. INTERNAL EXAMINATION OF THE BODY. 

Opening of the Abdominal Cavity, 27. — Inspection of the Abdominal Cavity, 
29. — Opening of the Thorax, 30. — Inspection of the Pleural Cavities, 31. — 
Opening of the Pericardium, 32. — External Inspection of the Heart, 32. — 
Opening of the Heart, ^^. — Removal of the Lungs, 37. — Organs of the Neck, 
39. — The Abdominal Cavity, 40. — The Spleen, 41. — The Gastro-intestinal 
Tract, 41. — The Liver, 44; The Kidneys and Adrenals, 45. — The Pelvic 
Organs, 47. — Removal of the Brain, 50. — External Examination of the Brain, 
55. — Section of the Brain, 56. — Yirchow's Method, 58; Pitre's Method, 59. — 
Pvemoval of the Spinal Cord, 60. — The Eye, 62. — The Ear, 63. — The Naso- 
pharynx, 64. — Examination of New-born and Very Young Children, 65. — 
Restitution of the Body, 67 



PART II. 

BACTERIOLOGICAL METHODS. 

I. CULTURE=MEDIA. 

The Preparation of Test-tubes, 70. — Preparation of Culture-media : 
Bouillon, 71; Glucose Bouillon, 73; Agar-agar (Plain), 74; Glucose Agar- 
agar, 77. — Glycerin Agar-agar, 77; Gelatin (Plain), 78; Glucose Gelatin, 79; 
Blood-serum (Lofner's Mixture), 79; Litmus-milk, 82; Potato-cultures Accord- 
ing to Bolton, 82; Dunham's Pepton Solution, 83. — The Adjustment of the 
Reaction of Culture-media by Titration, 83. — The Filling of Test-tubes. 85. — 
Sterilization of Culture-media, 87. — The Autoclave. 8S. — The Storage 
of Culture-media, 89. 

13 



14 CONTENTS. 

II. BACTERIOLOGICAL EXAMINATIONS. 

Methods of Collecting Material, 89. — Cover-glass Preparations, 92. — Staining 
Methods for Cover-glass Preparations: Simple Staining, 94; Pappenheim's 
Pyrosin and Methyl-green Mixture, 94; Gram's Method of Staining, 94. — 
Examination by Cultures, 95. — Method of Preparing Cultures on Blood-serum, 
96. — The Platinum Wire or Loop, 96. — Cultures from Blood During Life, 98. — 
The Inoculation of Animals, 99. 

HI. THE METHODS OF STUDYING BACTERIA IN CULTURES. 

1. Cover-glass Preparations from Cultures, 100. — The Staining of 
Spores, 101.— The Staining of Flagella, 102; Loffler's Method, 103; Pitfield's 
Method as Modified by J. Blackburn Smith, 104; Bowhill's Method, 104; 
S. H. Neuman's Method, 105 ; Williams' Method, 105. — 2. Methods of 
Obtaining Pure Cultures, 107. — Method of Isolation of a Bacterium in 
Pure Culture from a Mixed Growth, 109; The Plate Method of Petri, no; 
Esmarch's Method of Roll cultures, 112. — The Determination of the Motility 
of Bacteria, 1 13 ; H. W. Hill's Hanging-block Method for the Observation of 
Developing Bacteria, 114; Celloidin Sacs, 1 15. — 3. The Inoculation of 
Animals, 116. — Guinea-pigs, 116. — Rabbits, 117. — Mice, 119. — The Care of 
Animals, 120. — 4. Cultivation without Oxygen (Anaerobic Cultures) : 
Culture-media for Anaerobic Bacteria, 121 ; Method of Liborius, 122; 
Esmarch's Method, 123; Simple Anaerobic Plate-cultures, 124; Buchner's 
Method, 124; Wright's Method, 125; A Simple Method for Anaerobic Culti- 
vation in Fluid Media, 126; Bouillon Cultures under Hydrogen, 128; Cultures 
under Hydrogen or Solid Media, 129. 

IV. SPECIAL BACTERIOLOGY. 

Staphylococcus Pyogenes Aureus, 131. — Staphylococcus Pyogenes Albus and 
Citreus, 134. — Staphylococcus Epidermidis Albus, 134. — Staphylococcus Cereus 
Albus and Flavus, 134. — Streptococcus Pyogenes, 134. — Erysipelas, 138. — 
Pneumococcus, 138; Methods of Staining the Capsule of the Pneumococcus : 
Welch's Method, 142 ; W. H. Smith's Method, 142 —Streptococcus Capsu- 
lars, 143.— Gonococcus, 145; Special Culture-media, 146; Diagnosis, 148; 
Method of Staining for Gonococci, 150. — Micrococcus Catarrhalis, 151. — 
Micrococcus Tetragenus, 152. — Diplococcus Intracellulars Meningitidis, 153. — 
Bacillus Diphtherial, 157; Special Methods of Staining the Bacillus Diph- 
therias, 162; Neisser's Method, 162; Hunt's Method, 163.— Bacillus of 
Typhoid Fever, 163; Differential Diagnosis between the Bacillus of Typhoid 
Fever and the Bacillus Coli Communis, 167; The Blood-serum Reaction in 
Typhoid Fever, 168; Cultivation of the Typhoid Bacillus from the Blood dur- 
ing Life, 170 ; Cultivation of the Typhoid Bacillus from Rose Spots, 170. — 
Bacillus Coli Communis, 172: Detection of the Bacillus Coli Communis in 
Water, -176; Theobald Smith's Method, 177. — Paratyphoid and Paracolon 
Bacilli, 177. — Bacillus Dysenteric, 177. — Bacillus Tuberculosis, 180; Exami- 
nation of Sputum for Tubercle Bacilli, 184; Tubercle Bacilli in Urine, 186; 
Surgical Tuberculosis, 186. — Leprosy, 188. — Spirillum of Asiatic Chole-a 



CONTENTS. I 5 

(Comma Bacillus), 188 ; Bacteriological Diagnosis, 192. — Bacillus of Anthrax, 
195. — Bacillus Pyocyaneus (Bacillus of Green Pus), 199. — Bacillus of Bubonic 
Plague, 202. — Bacillus of Influenza, 205. — Bacillus of Glanders (Bacillus 
Mallei), 209. — Bacillus of Chancroid (Bacillus of Ducrey), 213. — Bacillus 
Proteus (Proteus Vulgaris), 215. — Baciilus Mucosus Capsulatus, 216. — Bacillus 
of Tetanus, 219; Method of Isolation, 222. — Bacillus Aerogenes Capsulatus, 
223. — Bacillus of Malignant Edema, 225. — Actinomyces, 226. — Mycetoma 
(Madura Foot), 232. — Rabies (Hydropholia), 235. 



PART III. 

HISTOLOGICAL METHODS. 

Introduction, 237. — Laboratory Outfit : Microscopes, 237. — Freezing Micro- 
tome, 239. — Celloidin Microtome, 242. — The Minot- Blake Microtome, 244. — 
Paraffin Microtome, 246. — Paraffin Bath, 246. — Vulcanized Fiber, 247. — 
Knives, 248. — Running Water, 249. — Slides, 250. — Cover-slips, 250. — Staining 
Dishes, 250. — Metal Instruments, 251. — Bottles, 252. — Examination of 
Fresh Material, 252. — Indifferent Fluids, 254. — Macerating Fluids, 254. — 
Examination of Fluids, 254. — Injections, 255. — Cold Injection-masses, 255. — 
Warm injection-masses, 256. — Fixing Reagents, 257. — Alcohol, 258. — 
Zenker's Fluid, 259. — Corrosive Sublimate, 260. — Orth's Fluid, 261. — Flem- 
ming's Solution, 261. — Hermann's Solution, 262. — Pianese's Solution, 262. — 
Formaldehyde, 262. — Wright's Method for Frozen Sections, 263. — Boiling, 266. 
— Miiller's Fluid, 266. — Marchi's Fluid, 267. — Decalcification, 267. — 
Directions for Using Nitric Acid, 268. — Phloroglucin and Nitric Acid, 268. — 
Sulphurous Acid, 269. — Trichloracetic Acid, 269. — Imbedding Processes, 
269. — Celloidin, 270. — Imbedding in Celloidin, 270. — Imbedding in Paraffin, 
274. — Serial Sections by the Celloidin Method, 277. — Serial Sections by the 
Paraffin Method, 279. — Wright's Imbedding Method for Frozen Sections, 279. 
— Staining Solutions: Hematoxylin and Hematein Stains, 280. — Carmine 
Stains, 285. — Aniline Dyes, 286. — Diffuse Stains, 291. — Combination Stains, 
292. — Pianese's Staining Solutions and Staining Methods, 293. — Orcein, 296. 
— Todin, 296.— Lugol's Solution, 296. — Acid Alcohol, 297. — Aniline Water, 
297. — Carbolic-acid Water, 297. — Mayer's Glycerin-albumin Mixture, 297. — 
Clearing Reagents, 297. — Mounting Reagents, 300. — Metallic Stains or 
Impregnations, 301. — Silver, 301. — Gold, 302. — Osmic Acid, 303. — Staining 
Methods, 304. — Nuclear Stains, 308. — Alum-hematoxylin Stains, 30S. — 
Aqueous Alum-hematoxylin; Delafield's Hematoxylin ; Ehrlich's Acid Hema- 
toxylin, 309. — Mayer's Hemalum, 310. — Heidenhain's Hematoxylin Stain, 310. 
— Heidenhain's Iron Hematoxylin, 3 1 1. — Mallory's Chlorid of Iron Hema- 
toxylin, 311. — Carmine Stains, 312. — Aniline Dyes as Nuclear Stains, 313. — 
Diffuse or Contrast-stains, 316. — Combination Stains, 317. — Staining in Mass, 
317. — Mitosis, 318. — Directions for Staining Karyomitotic Figures with 



1 6 CONTENTS. 

Safranin, 319. — Special Stains for Certain Tissue-elements other than 
Nuclei, 320. — Mastzellen, 320. — Plasma-cells, 321. — Connective-tissue Fibrillar 
and Reticulum, 322. — Fibroglia Fibrils, 324. — Elastic Fibers, 326. — Smooth 
and Striated Muscle-cells, 328. — The Central Nervous System, 329. — General 
Stains, 331. — Stains for Nissl or Tigroid Bodies, ^t>3- — Ganglion-cells; Den- 
dritic and Axis-cylinder Processes, 334 ; Axis-cylinders and their Terminal 
Processes, 338; Stains for the Myelin-sheath, 342; Stains for the Neuroglia- 
fibers, 348. — Degenerations of the Nervous System, 353. — Examination of the 
Blood, 354. — Apparatus Used in the Examination of the Blood, 355. — 
Preparation of Apparatus, 358. — Obtaining the Blood, 359. — The Hemoglobin 
Test, 360. — Estimation of Number of Red Corpuscles, 361. — The Elements 
of the Blood, 364. — Cover-glass Preparations, 368. — Methods of Staining, 369. 
— Methods of Fixing and Examining Special Organs and Tissues, 375. 
— Acute Inflammatory Exudations; Granulation-tissue, 376. — Lung, 377. — 
Spleen, Bone-marrow, 377. — Kidney, 37S. — Gastro-intestinal Tract, 378. — 
Liver, 378. — Bone and Cartilage, 379. — Skin, 3S2. — Museum Preparations, 
384. — Pathological Products, 385. — Cloudy Swelling; Albuminous Degen- 
eration, 385. — Fat, 386. — Necrosis, 3S8. — Caseation, 389. — Fibrin, 389. — 
Mucin, 390. — Pseudo-mucin, 392. — Colloid and Hyaline, 393. — Glycogen, 396. 
— Amyloid Infiltration, 398. — Pigmentation, 401. — Petrifaction, 404. — The 
Staining of Bacteria in Tissues, 405. — Pathogenic Bacteria which do not 
Stain by Gram, 407. — Gonococcus, 408 — Typhoid Bacillus, 408. — Influenza 
Bacillus, 40S. — Glanders Bacillus, 409. — Chancroid Bacillus, 410— Fried- 
lander's Capsule-bacillus, 410. — Pathogenic Bacteria which Stain by Gram, 410. 
— Bacillus of Rhinoscleroma, 411. — Actinomyces, 412. — Bacteria that Stain by 
the Tubercle-bacillus Method, 413.— Tubercle Bacillus, 413.— Bacillus of 
Leprosy, 415.— Syphilis Bacillus, 416.— Smegma Bacillus, 416.— Methods of 
Examination of Animal Parasites, 417.— Malarial Organisms, 417-— 
Amoeba Coli, 422.— Sporozoa, 425.— -Round-worms, 425. — Trichinae, 426.— 
Tape-worms, 427.— Taenia Solium, 427.— Taenia Mediocanellata s. Saginata, 
428.— Taenia Echinococcus, 429.— Bothriocephalus Latus, 429.— Clinical 
Pathology, 429. — Examination of Tissues from Clinical Cases for Diagnosis, 
430.— Uterine Scrapings, 430.— Examination of Fluids Obtained by Puncture, 
431.— Examination of Serous Fluids, 432.— Animal Inoculation, 437.— Lumbar 
Puncture, 437.— Ovarian and Parovarian Cysts, 440.— Pancreatic Cyst or Fistula, 
440. — Dropsy of the Gall-bladder, 441.— Hydronephrosis and Renal Cysts, 
441. — Echinococcus Cysts, 441. — Examination of the Sputum, 442. — Examina- 
tion of the Gastric Contents, 446.— Examination of the Feces, 448.— Examina- 
tion of the Urine, 448. 



PATHOLOGICAL TECHNIQUE. 



PART I. 
POST-MORTEM EXAMINATIONS. 



Introduction. — The method of making post-mortem 
examinations as originally taught by Virchow has been 
variously modified in its details by his pupils and followers. 
We have endeavored, while following in general his plan, to 
select those modifications that have proved simplest and of 
greatest value. In certain instances we have not hesitated 
to adopt, or at least to call attention to, useful methods of 
procedure originating in the Rokitansky school of pathology, 
as now best exemplified by Chiari. 

The problem offered by an autopsy is often solved in part 
or wholly by the macroscopic post-mortem examination. 
More frequently, however, the complete and final solution 
is reached only after careful bacteriological and histological 
study. The post-mortem examination may, therefore, be 
looked upon as the beginning of the solution of the prob- 
lem. Its particular function is to demonstrate in the indi- 
vidual case all congenital or acquired abnormalities, all 
macroscopic lesions, and to explain all gross mechanical 
questions. It furnishes the material for bacteriological and 
histological study. Perfectly to accomplish its purpose a 
post-mortem examination must be made in a careful, sys- 
tematic manner. 

While a general method of procedure is advisable, it will 
often be found advantageous, or even necessary, to depart 
2 17 



1 8 PATHOLOGICAL TECHNIQUE. 

from it. According to Orth, " the chief requisite of every 
exact post-mortem examination is this, that no part shall be 
displaced from its position until its relations to the surround- 
ing parts are established, and that no part shall be taken out 
by whose removal the further examination of other parts is 
affected." 

The order and method of procedure m making a post- 
mortem examination, including the various incisions, may be 
said to have been planned for the routine examination of 
normal or diffusely diseased organs. As soon as a notice- 
able focal lesion is present the order of procedure and the 
customary method of removal and of incision must be so 
altered as best to display the lesion. 

Instruments. — The following instruments will be found 
extremely useful in the autopsy-room, although not all of 
them are necessary : 

The autopsy-table should be large, so as to accommodate 
on it the instruments and several dishes in addition to the 
body. It should have a slightly raised edge, and should 
slope gently toward an opening in the center for the escape 
of fluids. The table is best made of zinc, and along one 
edge should have a centimeter scale. The water for use on 
the table is best supplied by a rubber tube from an overhead 
pipe reaching to within 60 to 100 cm. of the table. 

The scales for weighing the various organs should have a 
large pan and gram and kilogram weights. 

A band-saw will be found very useful for sawing bones for 
the inspection of the marrow, and for calcified and osseous 
tumors. 

The best autopsy-knife is a stout, broad-bladed knife with 
bellied edge and heavy handle. The blade should measure 
about 12 cm. in length and 3 cm. in width ; the handle should 
be 12 cm. in length. Many operators prefer a somewhat 
smaller knife than this. 

Amputating-knives of different sizes are useful for long, 
deep cuts into organs and tumors. 

A myelotome is a short, thin, narrow knife-blade, 1.4 cm. 
long and 4 mm. wide, set obliquely on a slender steel stalk 



POST-MORTEM EXAMINATIONS. 



19 



ending in a wooden handle (Fig. 2). It is used only for 
cutting the cord squarely across in removing the brain. 




hlT I -~ In i ^ mmentS for use in the autopsy-room: a, saw; », holder for the 
head ; c, steel hammer with wedge end and blunt hook on the handle ; d costo- 
tome ; e, bone-cutter; / hatchet-chisel ; gy autopsy-knife. 

Cartilage-knives and scalpels of different sizes are useful 
for a variety of purposes. 

Scissors, both straight and curved, should be oi various 



20 PATHOLOGICAL TECHNIQUE. 

sizes. A medium-sized and a fine pair should each have 
one probe-pointed blade. 

An enterotome is a long, straight pair of scissors, of which 




Fig. 2. — Myelotome. 



one blade is longer than the other and blunt at the extremity 
(Fig. 3). A hook at the end is not advisable. The instru- 
ment is used in opening the heart and the intestines. 




Fig. 3. — Enterotome 



A saw with movable back and rounded end will be found 
the most generally useful for opening the skull and the 




Fig. 4. — Luer's double rachiotome. 

spinal canal. An ordinary meat-saw is preferred by some, 
but cannot be used on the vertebrae. 

Luer's double rachiotome ', or adjustable double saw (Fig. 4). 
is very useful in removing the cord, and is the safest instru- 
ment to put into the hands of beginners. 



POST-MORTEM EXAMINATIONS. 21 

Forceps : several sizes, large and small, mouse-toothed. 

Costotome : heavy bone-shears for cutting the ribs. 

A powerful bone-cutter, with short blades, 5 cm. long, set 
at an angle of about 45 ° to the handles, which are 36 cm. 
in length, is employed for dividing the arches of the cervical 
vertebras and for other purposes where ordinary bone-cutters 
will not do. 

A chisel with 2 cm. cutting edge, for exposing the marrow 
of the long bones, removing portions of the base of the 
skull, etc. 

A hatchet-chisel of steel for starting the calvaria and spinous 
processes after sawing the skull and the vertebral column. 

Soft-iron hammer with wooden handle. 

Steel hammer with wedge end, and blunt hook on the 
handle. 

Holder for the head while sawing the skull. 

Autopsy-needles, long and a little curved. 

Probes of flexible metal ; also fine glass probes for small 
blood-vessels or ducts. 

Grooved director. 

Pans for holding water, organs, etc. 

Boards, square or oblong, 30 X 30 or 30 X 50 cm., on 
which to lay instruments or cut organs. 

Sponges. 

Catheters. 

Strong hemp twine is the best for sewing up the body. 

Glass graduates for measuring fluids. 

A block of zvood with shallow depression for the neck ; for 
use while opening the head. 

Vise. 

Small cup or dish for removing fluid from cavities. 

General Rules. — The room for an autopsy should be 
well lighted, otherwise the finer changes in the tissues cannot 
be recognized. Artificial illumination is not good, because 
the colors of the tissues are entirely changed by the yellow- 
ness of the light. 

Before beginning an autopsy the necessary instruments 



22 PATHOLOGICAL TECHNIQUE. 

should be arranged on a short board on the autopsy-table in 
the order in which they are most likely to be used. 

The operator stands on the right side of the body. This 
position he rarely leaves except for some definite purpose ; 
for example, in opening the skull he stands at the head. 

Order and cleanliness are the first points to be insisted 
upon at every autopsy. Clean water should always be at 
hand for washing the instruments and for keeping the hands 
free from blood and pus. The cut surface of an organ should 
not be washed with water except to remove blood ; gently 
scrape the surface with the knife held obliquely. 

In cutting, the knife should be drawn, not pressed or 
shoved into the tissues. According to Virchow, a broad, 
clean cut into an organ, even if incorrectly made, is much 
better than several short cuts which leave a ragged surface. 

The autopsy-knife should be grasped in the hand as if to 
cut bread. In using this knife the main movement should be 
from the shoulder, not from the wrist as in dissecting. It 
goes without saying that the sharper the knife the better. 

In cutting the brain and cord, especially if their consistency 
is lessened, moisten the knife to prevent the tissue from stick- 
ing and tearing. 

Before beginning an autopsy it is important to know the 
main points in the clinical history of the case, as they may 
greatly lighten the work of investigation by calling attention 
to those organs that require special examination. 

The record of an autopsy should be dictated by the ope- 
rator as he proceeds with the examination of the case, and 
should be as nearly as possible an objective description of 
the appearances found. Only the anatomical diagnosis 
should express the opinion of the operator. If it is not 
convenient to dictate the autopsy during its performance, 
the description of the lesions certainly ought to be made 
with the organs in sight, and not from memory after the 
lapse of hours or even days, when many of the details may 
be forgotten. Later, the results of the bacteriological and 
histological examinations should be added to the autopsy 
report, so as to make the case complete. 

The thin rubber gloves now used by surgeons are very 



POST-MORTEM EXAMINATIONS. 23 

useful in making post-mortem examinations, especially in 
septic cases and while opening the stomach and intestines. 
Rubber cots for the fingers are often useful. 

For cuts on the fingers use celloidin dissolved in equal 
parts of alcohol and ether, instead of flexible collodion, be- 
cause the latter will not stick. A cut received during an 
autopsy should immediately be washed thoroughly. For 
protection during the rest of the autopsy, use a rubber glove 
or cover the cut with celloidin. 

After an autopsy the operator should scrub his hands 
thoroughly with soap and brush, just as a surgeon does be- 
fore an operation, and then use, if he so desires, an antiseptic 
solution, such as corrosive sublimate (1 : 2000). For remov- 
ing odors from the hands, turpentine will often be found 
serviceable, or a saturated solution of permanganate of 
potassium followed by oxalic acid. 

For infections of slight wounds, such as scratches, or such 
as occur in hair-follicles, the best treatment within the first 
twenty-four hours is to bore into them with a sharp-pointed 
orange-stick dipped in strong carbolic acid. The procedure 
is practically painless, and the infection is stopped in the 
very beginning. Where the infection has spread, surgical 
treatment must be resorted to. 

Suggestions to Beginners. — In a case of general 
miliary tuberculosis the older focus from which the organ- 
isms have spread must always be found. Look especially 
for tubercular thrombi in the pulmonary veins as a frequent 
source of the general infection. 

In a case of embolism hunt for the thrombus, bearing in 
mind, however, that the whole of a thrombus may become 
free and form an embolus. An arterial embolus may be due 
to a venous thrombus, in which case it must have passed 
through an open foramen ovale, except in the case of 
thrombi of the pulmonary veins. 

In acute peritonitis always seek for a source of infection 
(appendix, female genitals, gastro-intestinal tract, etc.). It 
cannot always be found. 

In hemorrliagc from the stomacJi associated with cirrhosis 
of the liver look for rupture of dilated esophageal veins. 



24 PATHOLOGICAL TECHNIQUE. 

In cases of more or less sudden death, especially if pre- 
ceded by signs of asphyxia, always examine the pulmonary 
artery in situ for possible emboli. In cases of instantaneous 
death examine the coronary arteries. 

Private autopsies must often be made under many dis- 
advantages, and, when out of town, not infrequently in a 
short space of time. It is always important to warn the 
attending physician not to allow the undertaker to inject the 
body before the autopsy, because the color and consistency 
of the organs are so changed by most injecting fluids that it 
is difficult to recognize the pathological processes. If there 
is danger of post-mortem changes, have the body packed 
in ice. 

A regular autopsy-bag will be found very convenient for 
carrying to private autopsies. It is made of leather lined 
with rubber, and measures about 40 X 18 X 20 cm. Loose 
within it is carried a rubber bag 40 X 24 X 20 cm., shaped 
like a short envelope with a flap (22 cm. long) on one side, 
for bringing away any organs that demand further examina- 
tion. The case of instruments should contain one or two 
autopsy-knives, two scalpels, a pair of forceps, one or two 
pairs of scissors, an enterotome, a steel hammer with wedge- 
end and with a blunt hook on the handle, a small chisel, a 
saw with detachable handle and back, an autopsy-needle, 
and a probe ; free within the bag should be carried a spool 
of strong twine, a costotome, a long slender knife for use in 
removing the brain, a hammer with soft iron head, and a 
sponge. In rare cases additional instruments may be re- 
quired. A white duck apron for personal use will always 
be found convenient. It is also well to carry along several 
blood-serum tubes and a platinum needle for making cultures 
at the autopsy. When there is a lesion of the nervous sys- 
tem it is advisable to bring a jar of a 4 per cent, solution of 
formaldehyde and to place the tissue in the fluid at the 
autopsy, as otherwise it is not easily gotten to the laboratory 
in good condition. 

At the house can always be obtained a slop-pail, a wash- 
bowl, a pitcher of water, several newspapers, and an old 
sheet. The body is usually on an undertaker's frame, but 



POST-MORTEM EXAMINATIONS. 25 

it may be in an ice-box or on the bed. The examination of 
the chest and abdomen can be made in any of these posi- 
tions. If, however, the body is in an ice-box, it must be 
raised to the level of the top of the box in case it is neces- 
sary to open the head. 

The clothing on the body can be removed, or, if only a 
shirt or a night-dress, is best slit down the middle and turned 
out over the arms. Tear the sheet into four equal pieces. 
Fold and tuck in one piece on each side of the trunk and 
neck, allowing the outer portion to fall over the arms. Fold 
and lay the third piece on the lower extremities, tucking the 
upper end beneath the clothing below the pubes. The 
fourth piece can be placed beneath the head if it is to be 
opened. This procedure leaves the front of the thorax and 
abdomen free for operation and protects the rest of the body 
and the clothing. On the thighs place one or two folded 
newspapers, and on these the necessary instruments. On the 
legs place the bowl containing only a dampened sponge. 
If the undertaker has not put a rubber sheet on the floor 
beneath the body and on the side where the operator is to 
stand, newspapers should be spread to protect the carpet. 
Place the slop-pail on the rubber sheet within convenient 
reach. Having thus made all arrangements, even to the 
threading of his needle, the operator is ready to begin. 

If the cord and brain have to be examined as well as the 
body, it is best to do the cord first, so as to avoid the leak- 
age that might otherwise occur from the trunk-cavities if 
they had been opened first. To support the head while 
opening it, use a stick of wood, a brick, or, in case of neces- 
sity, the instrument-box wrapped in a newspaper. 

At a private autopsy cleanliness is extremely important. 
If there is no undertaker or nurse present, the operator 
himself must see that everything is cleaned and put in order 
before leaving, that all the blood-stains are removed from the 
dishes, and that all papers and soiled cloths are burned or 
rolled up and left in a neat bundle for the undertaker to dis- 
pose of. Ground coffee thrown on a shovelful of burning 
coals will be found helpful in disguising the odor in the 
room after an autopsy. 



26 PATHOLOGICAL TECHNIQUE. 

EXTERNAL EXAMINATION OF THE BODY. 

External examination is often of great importance, espe- 
cially in medico-legal autopsies, and should never be ne- 
glected, as it may throw great light on lesions found within 
the body. It should be systematic and careful, and is best 
taken up in the following order: 

1. Inspection of the Body as a Whole, 
i. Sex. 

2. Age. 

3. The body-length should be measured on the table beside 
the body, between points opposite the vertex of the head 
and the sole of the foot beneath the ankle. 

4. The development of the skeleton has reference to the 
bony framework, which may be powerful, slender, or de- 
formed. 

5. The general nutrition is shown by the amount of mus- 
cular development and of subcutaneous fat-tissue. The 
latter is judged by pinching up folds of skin. 

6. The general condition of the skin includes amount of 
elasticity, bronzing, jaundice, edema, and decubitus. 

7. Post-mortem discolorations may be divided into three 
varieties : 

(a) Hypostasis of blood, or the settling of blood into the 
lowest lying blood-vessels ; this form of discoloration dis- 
appears on pressure. 

(b) Diffusion of blood-coloring matter out of the vessels into 
the surrounding tissues (due to blood-pigment being set free 
by post-mortem decomposition) ; does not disappear on 
pressure. 

(c) The greenish discoloration, usually seen earliest over 
the abdomen, is due to sulphide of iron formed through 
decomposition of the tissues. This discoloration is import- 
ant, as it may modify the interpretation of appearances 
observed in the internal organs. 

8. Post-mortem rigidity, degree and extent. It begins in 
the maxillary muscles, and spreads gradually from above 
downward, disappearing later in the same order. It is most 
marked and lasts longest in muscular individuals who have 



POST-MORTEM EXAMINATIONS. 2J 

been ill but a short time. Cholera furnishes the most marked 
cases. The rigor disappears quickest in cachectic diseases. 
When once it has been forcibly overcome, it does not recur. 
The time of beginning after death varies widely — from ten 
minutes to seven hours. 

II. Special Inspection of the Different Parts of the 
Body. 

The examination should begin with the head. Any lesion 
or abnormality found should be carefully noted. Particular 
attention should be paid to the condition of the pupils and to 
the color of the sclera. Then follow in order the neck, the 
thorax (size and shape), the abdomen (distended or retracted), 
the genitals, and the extremities. 

INTERNAL EXAMINATION OF THE BODY. 

The opening of the body-cavities is described first, be- 
cause the brain is relatively much less frequently the seat of 
disease, and because in this country it is often impossible to 
obtain permission to open the head. Moreover, the lesions 
in the body often throw much light on those to be expected 
in the brain. The advantage of examining the brain first, 
particularly in those cases in which the important lesions 
are cerebral, is said to be that the amount of blood in the 
cerebral vessels can be more accurately determined. After 
the heart has been removed some of the blood in the brain 
may escape through the severed vessels below. 

In routine examinations, however, the body is usually 
examined first, then the brain, and finally the cord. It is 
not a bad practice to remove the calvarium, to examine the 
meninges over the upper surface of the cerebrum, and then 
to make the examination of the body before removing the 
brain. In this way any change in the blood-supply of the 
cerebral vessels would be observed. 

Opening of the Abdominal Cavity. — In the exam- 
ination of the body the peritoneal cavity is opened first, the 
two pleural cavities next, and the pericardial cavity last. The 
cavities and their contents are to be inspected in the order 
and at the time that each is opened, but the organs are to 



28 PATHOLOGICAL TECHNIQUE. 

be removed from the cavities for further examination in the 
reverse order, beginning with the heart. 

The primary or long anterior incision to bare the thorax and 
to open the abdomen (Fig. 5) should extend from the larynx 
to the pubes, passing to the left of the umbilicus, so as not 
to cut the round ligament. In cutting, the handle of the 
knife is depressed so as to use the belly of the blade rather 




FlG. 5.— Primary incision in the body (Nauwerck). 



than the point. An incision beginning as high as the chin 
is, unfortunately, rarely allowable. Over the sternum the 
cut should extend down to the bone ; over the abdomen, 
however, only into the muscles, or in fat people through the 
muscles into the subperitoneal fat-tissue. To open the ab- 
dominal cavity, nick carefully through the peritoneum just 
below the sternum, introduce the first and second fingers of 



POST-MORTEM EXAMINATIONS. 29 

the left hand, and while making strong upward and outward 
traction on the right abdominal flap extend the incision to 
the pubes. Some operators prefer to separate the fingers 
and to cut between them. 

The abdominal flaps are rendered much less tense by cut- 
ting the pyramidales and recti muscles from below just above 
the pubis. Care must be taken not to injure the overlying 
skin. The abdominal cavity can now be examined, but 
more room will be obtained if the skin and the underlying 
muscles be first stripped back from the thorax to about 5 
cm. outside of the costochondral line. 

The operation is most easily and neatly done by lifting the 
skin directly away from the chest- wall or turning it forcibly 
out with the left hand, and then cutting the tense tissue close 
to the cartilages and ribs with long sweeps of the knife held 
almost flat. The operation begins over the lower border of 
the ribs and extends upward. In dissecting off the skin and 
muscles from the left side the right hand works underneath 
the left. The mammae can easily be incised from the under 
side of the flap, and if necessary the axillary lymph-nodes 
can be reached by dissecting the skin farther out, especially 
over the clavicle. Before beginning the inspection of the 
peritoneal cavity it is important to examine first the surface 
of the incision into the abdomen, noting the thickness and 
color of the fat-tissue and the condition of the muscles. 

Inspection of the Abdominal Cavity. — The character 
of any fluid present should be determined and its amount 
measured or estimated. The simplest way to remove it is to 
dip it up with a small cup or dish and pour it into a glass 
graduate for inspection and measurement. If the presence 
of gas within the peritoneal cavity is suspected, a small 
pouch should be formed in the first incision as soon as it has 
been made and water poured in. The first opening into the 
abdominal cavity should then be made with the point of a 
scalpel at the bottom of the water, through which the gas, 
if present, will escape in bubbles. 

The various abdominal organs and their relations to each 
other are to be investigated in situ by sight and by touch. 



30 PATHOLOGICAL TECHNIQUE. 

As a rule, examine first the gastro-intestinal tract, including 
the appendix and the mesenteric lymph-nodes. Ulcerations 
of the intestine can often readily be made out through the 
walls. The examination of the spleen, liver, kidneys, and 
pelvic organs follows. The pancreas is easily reached by 
tearing through the omentum between the stomach and the 
colon, so as to open the lesser peritoneal cavity. 

After the inspection of the abdominal organs the position 
of the diaphragm is to be ascertained on both sides in the 
costochondral line by measuring with the right hand passed 
palm upward underneath the ribs, and the left hand outside 
at the corresponding height to mark the position of ribs or 
intercostal spaces. On the right side the hand is to be 
passed up on the outside of the falciform ligament. Nor- 
mally, the diaphragm stands at the fifth rib on the left side, 
and at the fourth rib or fourth interspace on the right. 

Opening of the Thorax. — To open the thorax, cut 
through the cartilages close to the ribs from the second 
down (about 5 mm. distant) with a scalpel held nearly hori- 
zontal, so that as one cartilage is cut through the handle of 
the scalpel will strike the next below and prevent the blade 
from penetrating too far and injuring the lung. In young 
people the cartilages can be cut easily by one long stroke on 
each side, but care must be taken not to go too deep. If 
the intercostal muscles are not divided by the same opera- 
tion, the sternum can be depressed by the left hand and the 
muscles severed by one pass of the knife on each side. The 
lower end of the sternum can now be elevated and freed 
from below upward from the diaphragm and pericardium 
until the first rib is reached. The cartilage of this rib is to 
be cut about 1 cm. farther out than the others, and from 
below upward toward the clavicle, with the handle of the 
knife beneath the elevated sternum and with the point and 
edge of the knife directed upward and a little outward. The 
sternum is then to be still further freed from the anterior 
mediastinal tissue until its upper end is reached. The sterno- 
clavicular joint on the left side can now be easily opened 
from below by entering a scalpel just above the cartilage of 



POST-MORTEM EXAMINATIONS. 3 1 

the first rib, and following the irregular line of the joint 
around the end of the clavicle, while at the same time draw- 
ing the sternum over to the right side of the body. The 
right sterno-clavicular articulation is to be opened by con- 
tinuing the incision of the scalpel over the upper end of the 
sternum and into the second joint. The advantage of this 
method is that there is much less danger of wounding the large 
vessels at the base of the neck, and thus of mingling blood 
with any exudation which may happen to be present in the 
pleural cavities. If preferred, however, the articulations can 
be opened and the cartilages of the first ribs cut from above 
before freeing the sternum from the diaphragm. In this case 
enter a short, sharp, narrow-bladed scalpel held vertically, 
but loosely, into the left joint on its upper side, starting the 
incision just outside of the attachment of the sternal end of 
the sterno-mastoid muscle, and cut around the end of the 
clavicle by a series of short up-and-down strokes, allowing 
the blade to follow the irregular line of the joint. After cut- 
ting through the joint continue the incision outward and cut 
through the cartilage of the first rib. 

If the cartilages are calcified, use the costotome and cut 
through the ribs, as more room can be gained in this way, 
and they are more easily cut than calcified cartilages. When 
for any reason it is not permitted to open the thorax, the 
organs within it can be obtained through the opening into 
the abdominal cavity by freeing the diaphragm from the ribs, 
and removing first the heart and then the lungs. The 
sternum should be inspected at the time of its removal. It 
is perhaps best to examine next, especially in children, the 
epiphyses of the ribs at the costochondral line for any evi- 
dence of thickening. 

Inspection of the Pleural Cavities. — In the pleural 
cavities, as in the peritoneal cavity, the character and amount 
of any abnormal contents must be determined. If, from the 
clinical history or from any other reason, the presence o\ 
air in a pleural cavity is suspected, a pouch should be formed 
over the ribs by aid of the skin-flap and filled with water. 
The pleural cavity is then to be pierced with a scalpel 



$2 PATHOLOGICAL TECHNIQUE. 

through the bottom of the pouch. Air, if present, will 
bubble up through the water. 

Slight adhesions are best torn through or cut. If the 
lungs are firmly attached, it is best to strip off the costal 
layer of the pleura with the lung. This is most easily done 
by starting the anterior edge of the costal pleura with the 
handle of the scalpel, and forking in first a finger and then 
the whole hand until the pleura is entirely free. In passing 
the hand into the pleural cavities protect the back of it, 
especially if the ribs have been cut through, by folding the 
skin-flap in over the edge of the ribs. 

If desired, the lungs can be drawn forward, examined over 
their whole extent, even incised, and then replaced until the 
heart has been removed. In the connective tissue of the 
anterior mediastinum there is almost always a certain amount 
of emphysema due to the removal of the sternum. Emphys- 
ema due to laceration of lung-tissue is more marked in the 
upper half of the mediastinum, and usually extends up into 
the neck. The thymus gland attains its full development at 
the end of the second year, after which time it usually 
gradually disappears. 

Opening of the Pericardium. — To open the pericar- 
dium, seize the sac near the middle with fingers or forceps, 
snip through the wall with knife or scissors, and with either 
instrument cut upward to where the pericardium is reflected 
over the large vessels, downward to the lower right border, 
and lastly to the apex. By gently raising the apex of the 
heart the amount of fluid in the pericardial cavity can be 
seen. The normal amount is about a teaspoonful, but it may 
be increased to ioo c.c. in cases where the death-agony is 
prolonged. Pericardial adhesions should be broken through 
with the fingers. If this is impossible, the heart must be 
incised through the pericardium. 

External Inspection of the Heart. — Determine first 
the position, size, and shape of the heart, and the degree of 
distention of the different parts. The right ventricle and 
both auricles are usually distended with blood, which may 
be fluid as in death from suffocation or more or less coagu- 



POST-MORTEM EXAMINATIONS. 33 

lated. The left ventricle is contracted and empty unless the 
individual has died from paralysis of this part of the heart, 
when it will be found distended with blood (condition of 
greatest diastole). 

Opening" of the Heart. — The heart may be opened in 
situ or after removal from the body. Except in certain cases, 
to be spoken of later, it usually will be found advisable to 
remove the heart before making any incision into it, for the 
reason that it can be more perfectly opened after removal, 
especially by beginners, and the danger of contaminating 
any bacterial lesions of the valves is lessened. 

To remove the heart, grasp it gently near the apex with 
the left hand, supporting it further, if necessary, by one or 
two fingers placed above the coronal suture, and lift the 
whole heart vertically upward. Then cut its vessels from 
below upward with the knife held transverse and oblique. 
Divide in turn the inferior vena cava, the pulmonary veins on 
both sides, the superior vena cava, the pulmonary artery, 
and the aorta. Go deep enough to remove the auricles 
entire, but avoid injury to the underlying esophagus. 

For making the incisions to open the heart either a long, 
slender-bladed knife or long, straight scissors may be used. 
The heart should be placed on a board with its anterior sur- 
face up. The right auricle is opened by cutting from the 
orifice of the inferior vena cava into that of the superior, 
and from the latter into the auricular appendage. The first 
incision to open the right ventricle is m,ade through the tri- 
cuspid valve and the wall of the ventricle along the under 
surface of the right border of the heart. It should be 
carried to the end of the ventricle, which does not reach 
quite to the apex of the heart. The second incision begins 
about the middle of the first, just above the insertion of the 
anterior papillary muscle (which should not be cut), and is 
carried through the pulmonary valve well over on the left 
side along the left border of a narrow, projecting ridge of 
fat-tissue usually present, so as to pass between the left ante- 
rior and the posterior segments of the valve. 

The left auricle is opened in a manner similar to the right 
3 



34 PATHOLOGICAL TECHNIQUE. 

by incisions joining the four orifices of the pulmonary veins 
and extending into the auricular appendage. 

The first incision into the left ventricle is through the 
mitral valve along the left border of the heart (/. e. the 
middle of the external wall of the left ventricle), between 
the two bundles of papillary muscles, to the apex of the 
heart. The second incision begins at the termination of the 
first at the apex, and is carried up close to the interven- 
tricular septum, parallel to the descending branch of the 




Fig. 6. — Heart, showing incisions. 

anterior coronary artery and about I cm. from it. The 
upper portion of the incision should pass midway between 
the pulmonary valve and the left auricular appendage. 
Ordinarily, one of the aortic cusps is divided, but this may 
be avoided, if desired, by dissecting away to some extent the 
pulmonary artery from the aorta and carrying the incision 
well over to the right between the right posterior and ante- 
rior valve-segments. As each auricle is opened the blood 
and clots it contains should be carefully removed and the 
auriculo-ventricular valves carefully inspected from above. 
In certain cases — as, for instance, extreme stenosis — it may 
be preferable not to cut through the valve, but to begin the 



POST-MORTEM EXAMINATIONS. 35 

incision in the ventricular wall below the valve. The ven- 
tricular cavities should in like manner be freed from clots 
and the valves closely inspected. The coronary arteries 
should always be opened by means of small, narrow-bladed, 
probe-pointed scissors as far as they can be followed. The 
examination of the descending branch of the anterior artery 
is especially important. The posterior coronary is best 
opened by placing the tip of the left fore finger in the aorta 
over the orifice of the artery, and cutting from without in 
toward the finger-tip until the vessel is reached, when it can 
easily be slit up. In this way injury to the aorta is avoided. 

In cases of more or less sudden death with symptoms of 
asphyxia the pulmonary artery should always be opened in 
situ before removal of the heart, in order to examine for pos- 
sible emboli, because they often lodge just at the point where 
the vessels are severed in removing the heart and lungs, and 
easily may slip out unobserved. The simplest operation is 
to thrust a sharp-pointed scalpel through the artery just 
above the valve on the left side in the line of incision already 
described, and to cut upward until the branches to the right 
and left lungs are reached. If desired, this incision may be 
extended down through the pulmonary valve and the ven- 
tricular wall along the line given for the second incision in 
the right ventricle. 

The water-test for the competence of the valves of the 
heart is not very reliable, especially for the auriculo-ven- 
tricular valves, and is not so much used as formerly. 
Inspection and measurement of the valve after the heart 
has been opened will usually enable one to judge fairly 
accurately concerning the degree of competence. Before 
applying the test to the aortic valve the first incision into 
the left ventricle must be made and the cavity freed from 
clots, so that no obstruction will exist below the valve. 
Then the heart is to be held so that the aortic valve is per- 
fectly horizontal, and water poured in from above to float the 
cusps out. If competent, they should keep the water from 
flowing through. If, however, in holding the heart the nor- 
mal relations of the valve and the surrounding parts arc not 



36 PATHOLOGICAL TECHNIQUE. 

maintained, the valve may leak. A second source of error 
is that the water may escape through the coronary arteries, 
branches of which have been cut in opening the ventricle. 
In testing the mitral valve the left auricle is first opened and 
the clots removed, so as to expose the upper surface of the 
valve. Then the nozzle of a syringe is introduced through 
the aortic valve and water forced in so as to float the mitral 
curtains up. The test, however, is very unreliable, because 
the parts cannot be placed under natural conditions. 

The pulmonary and tricuspid valves can, of course, be 
tested by methods similar to those already described. 

Increase or diminution in the size of the heart is best 
determined by weighing the organ after the removal of the 
clots. In certain cases, however, and in special investigations 
measurements of different parts of the heart are desirable. 
Roughly, the heart is the size of the individual's fist. 

The following weights and measurements are taken from 
Nauwerck 's Sectionsteclinik : 

Weight of the heart averages in men, 300 gr. 1 ~ , 

" " " " women, 250 " > 

Krause gives the average weight of the heart as 292 gr. 

Relative weight of heart to body in men, I-169") ^ 

} y V Krause. 

" " " " women, 1-162 i 

Length of heart in men, 8.5-9 cm. \ „. 

" " women, 8.0-8.5 " > 

Circumference of heart at base of ventricles, 28.8 cm. {Sappey). 

Thickness of wall of left ventricle, 1.1-1.4 cm. 1 T ^ 

' \ Krause. 

" " right " 0.5-0.7 " i 

Thickness of wall of left ventricle (without trabeculae), 7-10 mm. ") ~ , 

right " " " 2-3 " J 

Circumference of mitral orifice, 10.4 (W.), 10.9 (M.) "] 

" " tricuspid " 12.0 (W.), 12.7 (M.) ( 

" aortic " 7.7 (W.), 8.0 (M.) f mUSe ' 

" " pulmonary orifice, 8.9 (W.), 9.2 (M.) J 

" " ascending aorta, 7.4 cm. 

" " pulmonary artery, 8.0 cm. [Buhl). 

The directions given for the removal and opening of the 
heart apply only when the organ is normal or contains 
lesions within itself which are not in continuity with any of 
the vessels entering into it. In aneurysm of the ascending 



POST-MORTEM EXAMINATIONS. 37 

aorta, in thrombosis of a vena cava, and in a number of dif- 
ferent lesions connected with the heart or with the vessels 
given off from it, it is important to examine these vessels 
and to open them while they are still in continuity with the 
heart. For this purpose it is often necessary or advantageous 
to remove the thoracic organs in one piece, so as to be able 
to examine the central circulatory apparatus in continuity 
from the front and back before disturbing any of its relations. 
This is done by cutting across the trachea and adjoining 
tissues as high in the neck as necessary or possible, and dis- 
secting them free from the cervical vertebrae and the first 
ribs. Then by drawing the trachea and surrounding tissues 
forcibly forward the aorta and overlying organs can be easily 
stripped from the vertebral column as low as the diaphragm. 
The left hand is now placed around the lower end of the 
pericardial sac, the aorta, and the esophagus just above the 
diaphragm, and the vessels are severed by cutting between 
the hand and the diaphragm. 

More space for the examination in situ of the vessels at 
the base of the neck can be obtained by freeing the clavicles 
from all attachments above and to the first ribs and drawing 
them forcibly outward ; this operation will be found especially 
useful in following up the subclavian vessels. 

Removal of the I/UngS. — Pleural adhesions have al- 
ready been spoken of. If the base of the lung is adherent 
to the diaphragm, it is usually advisable to remove the latter 
with the lung by cutting through its insertion into the ribs. 
According to Orth, there is less danger of wounding the ab- 
dominal organs if scissors be used for the performance of 
the operation. After the lung is free it is drawn forward 
out of the pleural cavity, and the root of it is grasped from 
above downward between the separated fingers (first and 
second or second and third) of the left hand. The lung, 
thus resting in the palm of the left hand, is first drawn 
downward toward the pubes until the primary bronchus is 
divided by a nearly vertical incision above and behind the 
left hand. Then the lung is lifted vertically upward, and the 
rest of its attachments cut in the same direction from above 



38 



PA THO L O GICA L TE CHNIQ UE. 



downward by the knife held transverse and flat, so as to 
avoid injuring the esophagus and aorta. 

The procedure is the same for both lungs. Once in a 
great while the apex of a lung will be found so firmly adhe- 
rent by dense scar-tissue that it can be freed only by using 
the knife. 

The primary or main incision into a lung is a long, deep 




Fig. 7. — Method of incising the lung (Nauwerck 



cut from the apex to the base and from the convex surface 
to the root, slitting the primary bronchus, and thus not cut- 
ting it off from its branches to the upper and lower lobes 
(Fig. 7). To incise the left lung, place it with its inner or 
median surface and root downward on a board and with its 
base toward the operator. The left thumb steadies the lower 
lobe ; the first finger reaches between the two lobes almost 
to the primary bronchus ; and the rest of the fingers should 
hold the upper lobe. 



POST-MORTEM EXAMINATIONS. 39 

The right lung is most easily incised by placing it in the 
same position, but with the apex toward the operator; in 
other words, always place the anterior edge of a lung beneath 
the palm of the hand. Some prefer to place each lung on 
its lower or diaphragmatic surface for incision. The right 
middle lobe is incised separately by a cut extending trans- 
versely in its greatest diameter. 

The bronchi and blood-vessels should be opened up for 
some distance with small probe-pointed scissors — as a rule 
from the surface of the section — cutting through the over- 
lying lung-tissue. In some cases, however, it is best to open 
up both the blood-vessels and the bronchi from the outside 
of the lung before incising it. The order to follow is vein 
first, then artery, and finally the bronchus. 

Secondary cuts into the lung are to be made parallel to 
the main incision. 

The bronchial lymph-nodes should be incised from the 
outside of the lung. 

Organs of the Neck. — The operation of the removal 
of the organs of the neck is greatly facilitated if it is pos- 
sible to continue the primary skin-incision up to the chin. 
In other cases dissect the skin from the larynx and muscles 
of the neck as far up as possible. In like manner free the 
muscles, esophagus, and trachea from their attachments later- 
ally and posteriorly. Then allow the head to drop well back 
over the end of the table, and pass a long, slender-bladed 
knife up between the skin and the larynx, just behind the 
symphysis of the lower jaw, until the point of the knife 
appears beneath the tip of the tongue. From this point the 
knife is carried with a sawing motion down first one ramus 
of the jaw and then the other, dividing laterally the glossal 
muscles as far back as the posterior pharynx. The knife is 
next carried up behind the esophagus, and the posterior wall 
of the pharynx divided as high as possible. Pass the left 
hand up inside of the neck and draw down the tongue. 
Then cut the attachments of the soft to the hard palate, 
carrying the knife well out so as not to injure the tonsils. 
Any remaining attachments are usually easily severed by 



40 PATHOLOGICAL TECHNIQUE. 

pressing the tongue first to one side and then to the other, 
and cutting close to the roof of the pharynx. 

Each lobe of the thyroid gland is to be incised in its 
greatest diameter. 

Next cut through the middle of the uvula and examine 
all of the pharynx removed. Incise the tonsils vertically. 
The esophagus is to be slit in the median line posteriorly; 
if it is normal, the larynx and trachea are then slit in the pos- 
terior median line also, thus splitting the esophagus in two. 

The Abdominal Cavity. — The order of removal of 
the abdominal organs varies with different operators, and 
under varying circumstances with the same operator. The 
gastro-intestinal tract, including the liver and pancreas, may 
be removed before or after the genito-urinary tract. The 
spleen as an organ by itself is often the first to be removed. 
The early removal of the liver is occasionally advantageous 
for the sake of the additional space obtained for the exami- 
nation of the other organs. It is well to practise the different 
methods of procedure, so that in a difficult case the best 
may be selected, because the examination of the abdominal 
cavity, especially in cases of extensive disease with numer- 
ous adhesions, is often one of the hardest tasks in post- 
mortem technique. As a rule, it is best to follow the usual 
order as long as possible, gradually removing the more or 
less normal or uninvolved organs. Occasionally it may be 
advisable to remove the organs en bloc, so as to be able to 
approach the problem from all sides. 

In all cases of acute peritonitis it is best before removing 
any organ to search for the source of the infection, paying 
particular attention to the vermiform appendix, to the gastro- 
intestinal tract, and, in females, to the pelvic organs. 

The order of removal of the abdominal organs adopted 
in this book for the majority of cases is that which seems 
the simplest and most natural — namely, to remove first the 
spleen as an organ essentially by itself; secondly, the gastro- 
intestinal tract, including the pancreas and liver, which forms 
the upper layer ; thirdly, the genito-urinary tract or middle 
layer, leaving the circulatory tract, the lowest layer, to be 
opened and inspected in situ. If, however, it proves neces- 



POST-MORTEM EXAMINATIONS. 4 1 

sary to open a part of the gastro-intestinal tract in situ, it 
will be neater perhaps to remove the kidneys and spleen 
first. Occasionally at private autopsies it may be unneces- 
sary to examine the intestinal tract ; under these circum- 
stances it is important to be able to get at the different 
organs without taking out the intestines. 

The Spleen/ — As a rule, the spleen can easily be drawn 
forward from its bed behind the fundus of the stomach, be- 
neath the diaphragm, and lifted on to the lower edge of the 
ribs on the left side without cutting its vessels. The organ 
is then to be incised in its greatest diameter while thus firmly 
fixed between the left hand and the ribs ; or the vessels may 
be cut close to the hilus and the spleen incised after being 
placed on a board. 

In cases of adhesion to the diaphragm the spleen must be 
handled carefully while the fibrous attachments are torn or 
cut through, for the capsule is easily ruptured. Occasion- 
ally it is advisable to cut out with the spleen the portion of 
diaphragm attached to it. 

The important anatomical structures to be noted in the 
macroscopic examination are the capsule, trabecular, blood- 
vessels, lymph-nodules, and pulp. The weight of the spleen, 
according to Orth, varies from 150 to 250 grams. The 
average weight is put at 171 grams. The spleen measures 
12 X 7.5 X 3 cm. 

The Gastro-intestinal Tract. — The first step is to 
examine externally, more or less carefully according to the 
clinical' symptoms, the whole tract from the stomach to the 
rectum, if it has not already been done at the primary in- 
spection of the peritoneal cavity. The main points to notice 
are distention or contraction of the intestines, injection of the 
blood-vessels, thickening of the wall, especially in the lower 
part of the ileum, adhesions, exudations, etc. Inspect the 
mesentery, its length, the amount of fat, and the size of the 
lymph-nodes ; incise the latter to determine color and con- 
sistency. Examine the mesenteric vessels if an}' evidence 
of infarction of the intestine is noticed. The portal vein and 
its branches should be opened up in situ, in all cases of ab- 



42 PATHOLOGICAL TECHNIQUE. 

scess of the liver or of secondary deposits in it of malignant 
growths, before the gastro-intestinal tract is removed. As a 
rule, it is not necessary to open any part of the gastro-intes- 
tinal tract in situ. The operation can be performed much 
more neatly at the sink. The duodenum is often opened for 
the sake of investigating the flow of bile from the gall-duct, 
but except in cases of jaundice the operation must be looked 
upon largely as a physiological experiment. 

Free the omentum from the transverse colon by putting it 
on the stretch and dividing it with the knife close to the 
colon. Then begin the removal of the large intestine by 
drawing the sigmoid flexure forcibly forward and cutting the 
mesocolon close to the gut, first down to the rectum, then 
upward to the transverse colon. Free the latter by dividing 
the two folds of the lesser omentum, if not already cut 
through, which unite it to the stomach. The ascending 
colon is to be freed in the same manner as the descending 
portion. Care should be taken not to injure the appendix. 
If the lower part of the sigmoid flexure be now stripped up- 
ward a short distance with the fingers, so as to force the in- 
testinal contents out of the way, the gut can be divided just 
above the rectum without fear of the feces escaping. 

Place the freed intestine in a pan or pail, and as the small 
intestine is divided from its mesentery deposit it in the same 
receptacle. To remove the small intestine, begin at the ce- 
cum, and, while lifting the ileum with the left hand strongly 
enough to keep the mesentery constantly tense, cut the latter 
close to the intestine by playing the knife easily backward 
and forward across it with a fiddle-bow movement. Con- 
tinue the operation until the duodenum is reached. The 
mesentery can now be dissected from the duodenum and re- 
moved, or the mesentery, duodenum, pancreas, and stomach 
can be removed in continuity with the intestine by carefully 
dissecting them off the underlying structures. The opera- 
tion is perhaps more easily accomplished by freeing the 
organs from below upward. First cut down through the 
diaphragm and free it around the esophagus. Then separate 
the stomach from the liver by means of the thumb and fingers 



POST-MORTEM EXAMINATIONS. 43 

of the left hand in such a way as to put on the stretch the 
vessels of the hepato-duodenal ligament. These vessels 
(hepatic artery, common gall-duct, and portal vein) are then 
carefully divided in the order named. As each vessel is cut 
the character of its contents should be observed to see if 
anything abnormal is present. 

The mesentery, if still present, the duodenum, the pan- 
creas, and the stomach, are now to be dissected carefully 
away from the underlying vessels from below upward until 
the esophagus is reached. This may be constricted by the 
fingers at any point desired, and cut across without danger 
of the gastric contents escaping and without the necessity 
of tying. In certain cases of hemorrhage from the stomach 
associated with cirrhosis of the liver it is important to re- 
move the esophagus in continuity with the stomach, because 
in these cases the hemorrhage usually takes place from 
dilated esophageal veins. 

The stomach and intestines are now to be opened at the 
sink by means of the enterotome, the colon along one of its 
longitudinal muscular bands, the small intestine along its 
mesenteric attachment, because the most important lesions 
usually occur opposite this line in the lymph-nodules and 
Peyer's patches. The stomach is opened by many along the 
greater curvature ; others, however, prefer to cut along a 
line 3 cm. from the lesser curvature, on the ground that 
better museum preparations are thus obtained. In case 
any tumor or focal lesion is perceived from the outside, it 
is advisable to cut the stomach, if possible, in such a way as 
to leave the pathological part uninjured. 

Whenever jaundice is present the duodenum must be 
opened in situ in order to examine the bile apparatus in con- 
tinuity, so as to determine whether the coloring is due to 
obstruction of the hepatic or common gall-ducts, or is of so- 
called hematogenous origin. 

To open the duodenum make a transverse fold in the ante- 
rior wall and incise with the scissors. Continue the longi- 
tudinal slit thus made up as far as the pylorus and down to 
where the duodenum passes beneath the mesentery. Notice 



44 PATHOLOGICAL TECHNIQUE. 

the contents of the duodenum and their color both above 
and below the opening of the gall-duct. The ductus cho- 
ledochus usually opens in common with the ductus pan- 
creaticus on the posterior wall of the duodenum a little 
below the middle of the head of the pancreas, at a point 
marked by a small papilla which can easily be recognized 
by putting the mucous membrane on the stretch transversely. 
Press first on the common duct gently and in the direction 
of the papilla, watching the opening to see if any obstructing 
material is forced out. Pressure is then to be made on the 
gall-bladder to see if its contents also will flow. If neces- 
sary, the common duct and its branches are to be opened in 
situ. In certain cases the ductus pancreaticus is likewise to 
be opened up. 

Several cross-sections of the pancreas are usually better 
than one in the greatest diameter, because the duct is left in 
a better condition for slitting up if necessary. The weight 
of the pancreas varies from 90 to 120 grams (Orth). It 
measures 23 X 4.5 X 2.8 cm. 

The Liver. — The liver is usually the last organ of the 
gastro-intestinal tract to be removed. This is ordinarily 
done by lifting up the right lobe and freeing it from all 
attachments as far as the vertebral column : the right lobe is 
then lifted and placed on the edge of the ribs on the right 
side, while the left lobe is elevated and freed. If the dia- 
phragm is firmly adherent, remove it with the liver. The 
incision to display the liver is a long deep cut passing through 
the right and left lobes in the greatest diameter of the organ. 

In a good many cases it is very convenient to remove the 
liver at the beginning of the special examination of the ab- 
dominal cavity, because more room can be obtained for the 
investigation of the other organs. This latter fault can to 
some extent be obviated by cutting the diaphragm on the 
right side and allowing the liver to slide forward somewhat 
into the right thoracic cavity. 

There can be no objection to the removal of the liver 
when jaundice is not present or when the liver is not con- 
nected by continuity with the lesion of some other organ 



POST-MORTEM EXAMINATIONS. 45 

(pylephlebitis, malignant growth extending through portal 
vein or along gall-ducts, etc.). 

The operation is performed as follows : Pass the left hand 
in between the diaphragm and the right lobe and push the 
liver forward out of the right hypochondrium. Incise it 
deeply in its greatest diameter through the left and right 
lobes. Next free the gall-bladder from its bed by means of 
the fingers, and cut it off near the ductus hepaticus after 
compressing its lower end. It can then be opened length- 
wise and washed without danger of discoloring the liver or 
other organs. The liver is now to be grasped by placing 
the thumb on the under surface of the liver and the fingers 
in the incision. Elevate the organ, and, while carefully 
watching, cut through the hepato-duodenal ligament, which 
includes the blood-vessels and the ductus hepaticus. The 
ligamentum hepato-gastrium, the inferior vena cava, the 
suspensory ligament, the ligamentum coronarium, and the 
tissue between the inferior surface of the liver and the upper 
end of the kidney follow next : the adrenal is to be left on 
the kidney, and the diaphragm ought not to be injured. 

Even in the ordinary way of removing the liver the organ 
will be found much easier to handle if the usual incision is 
made in situ, so as to furnish a'hold for the left hand. 

Other cuts into the liver are best made parallel to the 
primary one. 

Orth gives the weight of the liver for adults as varying 
from 1000 to 2000 grams. The average weight is usually 
put at 1500 to 1800 grams. 

The liver measurements are as follows : 

Length from right to left 2 5~3 2 cm. 

Width of right lobe 18-20 " 

Width of left lobe 8-10 " 

Vertical diameter of right lobe 20-22 " 

Vertical diameter of left lobe 1 5—16 " 

Greatest thickness 6- 9.5 " 

The Kidneys and Adrenals. — If the adrenals are to be 
removed with the kidneys, it is necessary to cut first to the 
inside, and secondly above the adrenal, and then to make 



46 PATHOLOGICAL TECHNIQUE. 

from the outer end of the second cut a curved incision along 
the outer convex border of the kidney through the perito- 
neum and the perinephritic fat-tissue. The left hand is to 
be inserted into the cut, the mass of tissue drawn forcibly 
forward, and the vessels divided as close to the aorta as pos- 
sible, so that the renal vessels may be slit up and examined 
in connection with the renal lesions. The adrenal should be 
incised crosswise. The kidney is to be held firmly in the 
left hand between the thumb and fingers while a longitudinal 
incision is made from the convex border to the hilus. As a 
rule, it is better to shell it out of its investing fat- tissue before 
incising it. 

It will often be found convenient to make simply the curved 
incision above given, to shell the kidney out of its fat-cap- 
sule, and then to divide its vessels, leaving the adrenal behind 
to be incised in situ or removed separately. As a rule the left 
kidney is removed first. 

In all cases in which the bladder is involved in patho- 
logical changes in common with the kidneys the whole 
urinary tract should be removed intact, so that the lesions 
may be examined in continuity. For this reason it is a good 
plan to open up the pelvis of the kidney and the ureter from 
the primary incision, in order to see if any lesion is present 
before dividing the ureter. 

If it is desired to remove the kidneys before the intestines, 
the latter must to some extent be freed from their normal 
attachments. 

The splenic flexure of the colon is first to be drawn for- 
cibly forward and its attachments divided where they hide the 
left kidney. If the ureter is to be taken out also, it is best 
to free the whole of the descending colon from its mesocolon. 
Then the colon and the coils of small intestine are drawn 
over to the right side of the body, so as to leave the left kid- 
ney and adrenal exposed. They are then removed in exactly 
the same manner as already described. 

To remove the right kidney the hepatic flexure must be 
freed from over it. If the ureter is to be taken out, the de- 
scending - colon and the cecum are dissected from over it. 



POST-MORTEM EXAMINATIONS. 47 

The right adrenal is firmly attached to the under surface of 
the liver, and must be carefully dissected from it by turning 
the latter upward. 

If the urinary tract is to be removed in continuity, each 
ureter is dissected down to the brim of the pelvis, and then 
left with its kidney attached until the pelvic organs have 
been taken out. 

After the kidney has been incised the capsule is to be 
stripped off, at least in part, so that the appearance of the 
surface of the kidney and the presence or absence of adhe- 
sions between the capsule and the renal tissue can be deter- 
mined. 

The points to be noted in the macroscopic examination of 
the kidney are size, consistency, and, on section, color, rela- 
tive proportion of cortex to pyramids, and thickness of each ; 
finally, the normal markings of the kidney, including blood- 
vessels, glomeruli, convoluted and straight tubules of cortex, 
collecting tubules of pyramids. 

The average weight of the kidney is 150 grams. The left 
kidney is always 5 to 7 grams heavier than the right (Orth). 
A kidney measures 11-12X5-6X3-4.5 cm. The cortex 
measures in thickness 4-6 mm. The relation of the cortex 
to the medulla is 1 to 3. 

The Pelvic Organs. — The pelvic organs are most easily 
and neatly removed by stripping the peritoneum from the 
pelvic wall with the fingers. Begin over the bladder and 
extend down the sides of the pelvis until the fingers meet 
beneath the rectum. Brace the backs of the hands laterally 
on the brim of the pelvis and lift the fingers forcibly upward ; 
this movement will free the pelvic organs cleanly from the 
sacrum, and leave them attached only anteriorly at the rectal 
and genital openings, and posteriorly by the peritoneum and 
the vessels at the brim of the pelvis. 

Anteriorly, the attachments may now be divided with the 
knife at whatever point seems advisable, ordinarily close to 
the pubes just anterior to the prostate (or through the ure- 
thra and vagina in females) and through the lower end of 
the rectum. Posteriorly, cut through the tissues at the brim 



48 PATHOLOGICAL TECHNIQUE. 

of the pelvis, taking care not to cut the ureters if the kid- 
neys are still attached to them. The rectum is to be opened 
with the enterotome along the posterior wall, and the inner 
surface thoroughly washed off so as to avoid soiling the 
other organs. 

To open the bladder in males, especially if the penis has 
been removed in continuity with it, incise with the scissors a 
transverse fold in the anterior wall of the fundus, and carry 
the incision through the urethra and along the dorsum of the 
penis. To accomplish the latter act perfectly the penis must 
be firmly stretched by having an assistant pull at the frenum 
while the bladder is held fixed by the operator. 

In females it is usual to enter the scissors into the bladder 
through the urethra and to cut through the middle of the 
anterior wall of the fundus. 

In males the rectum should be dissected from the bladder, 
so as to lay bare the vesiculae seminales and the prostate, 
which are examined by means of several transverse incisions. 

In females, if the bladder is normal, the vagina is incised 
in the anterior wall through the middle of the bladder. Or 
the vagina may be incised laterally until the cervix is reached, 
and then the cut be carried up to the median line. 

The uterus is incised in its anterior wall from the cervix 
to the fundus. From the upper part of this incision second- 
ary incisions are carried out on each side to the orifices of the 
Fallopian tubes. 

The ovaries are incised in their greatest diameter, from the 
convex border to the hilus. Weight of ovaries, 7 grams. 

The testicles can readily be examined without external 
injury to the scrotum by cutting underneath the skin over 
the pubes down to the scrotum on either side of the penis, 
and shoving the testicles up through the incision. Cut care- 
fully through the overlying tissues until the cavity of the 
tunica vaginalis is opened. Remove the testicle by severing 
the cord. The incision to display a testicle should be in the 
long diameter, beginning on the side opposite the epididymis 
and extending through into it. Weight of testicles, 15-24.5 
grams. In cases of tuberculosis of the testis and epididymis 



POST-MORTEM EXAMINATIONS. 49 

it is advisable not to cut through the cord, but to remove 
the testicles and cords with the bladder, so that the whole 
genital tract may be examined in continuity and the asso- 
ciated lesions in the vesiculae seminales demonstrated, if 
present. 

The penis, or at least the larger portion of it, can be re- 
moved in connection with the bladder by continuing the pri- 
mary body-incision out to about the middle of the dorsum 
of the penis, which is then to be freed from the investing 
skin and divided just posterior to the corona. It is next 
dissected back to the pubic arch, and freed from it partly by 
cutting from without, partly from within, the pelvis, until the 
penis can be passed underneath the arch into the pelvis. 
Other methods are to cut through the symphysis, which can 
then readily be sprung apart by swinging one of the legs 
out in a horizontal plane, or even to saw out a small sec- 
tion of bone including the symphysis, so as to have more 
room for freeing the attachment of the penis and for re- 
moving it. 

The structures now remaining in the abdominal and 
thoracic cavities which require examination are the large 
blood-vessels, the thoracic duct, the celiac ganglion, and the 
retroperitoneal lymph-nodes. The inferior vena cava and 
its branches are first examined (especially in all cases of 
pulmonary embolism) by slitting them with scissors along 
the anterior wall. If it is necessary to follow the iliac ves- 
sels into the thigh, it will be found easier in sewing up if the 
primary abdominal incision is continued off to the side in 
question, thus giving a single though curved incision. 

It is sometimes advisable to open up the inferior vena cava 
and its branches before removing the pelvic organs, so that 
thrombi extending into the pelvic vessels may be examined 
before they are disturbed. 

The semilunar ganglia lie on the aorta, around the celiac 
axis, above the pancreas. 

The thoracic dnct lies behind and to the right of the aorta. 
In the thorax it is most easily found by dissecting on the 
right side between the aorta and the azygos vein. The re- 
4 



50 PATHOLOGICAL TECHNIQUE. 

ceptaculum chyli lies to the right and behind the aorta upon 
the second or third lumbar vertebra. Examination of the 
thoracic duct is of especial importance in cases of tubercu- 
losis of the intestine and mesenteric lymph-nodes with 
secondary miliary tuberculosis. 

The aorta is to be opened in situ along the anterior wall 
throughout its whole extent, and the iliacs as far as the 
femoral ring. 

Besides the brain, the spinal cord, and the thoracic and 
abdominal organs, it is often necessary to examine or remove 
for study other portions of the body that are affected by dis- 
ease. A little ingenuity will enable one in appropriate cases 
to get at almost any part desired. 

A view of the marrow in a long bone is most easily ob- 
tained in the femur by extending the body-incision down 
over one of the thighs, dissecting the muscles way, and then 
chiselling off a portion of the upper part of the shaft. 

In tuberculosis of the spine it is quite easy to remove any 
part, or even the whole, of the vertebral column, including 
the pelvis and portions of the femurs, without other incisions 
than the one from the neck to the pubes, with extension 
down the thighs in case parts of the femurs are to be taken 
out. Divide the ribs a few centimeters from the vertebral 
column on each side of the portion that is to be removed, 
cut through intervertebral disks both above and below it, 
and then carefully dissect it free, taking great care not to 
button-hole the skin. 

Removal of the Brain. — The incision into the scalp 
should begin from one to two centimeters behind the right 
ear, near its lower border, at the edge of the hair, and ex- 
tend over the vertex of the skull to a corresponding point 
behind the left ear. The cut is most easily made by thrust- 
ing a small narrow-bladed scalpel, with its back toward the 
calvarium and its point toward the vertex, through the skin 
behind the ear and shoving it along in the desired direction. 
By making the incision in this manner the hair is not cut, 
but simply parted. The anterior flap should be stripped 
from the calvarium and the temporal muscles by putting it on 



POST-MORTEM EXAMINATIONS. 5 I 

the stretch and dividing the loose connective tissue hold- 
ing it by sweeping strokes of the scalpel nearly as far for- 
ward as the orbits. After a part of the flap has been freed 
it is often possible to strip the rest without using the scalpel. 
For the posterior flap, which should be removed back as far 
as the occipital protuberance, the scalpel nearly always has 
to be used. 

If the hair is long, the anterior portion can be rolled into 
the anterior flap over the face and thus protected. The 
posterior portion is gathered at the nape of the neck, and 
then a towel is wrapped tightly around the head and neck, 
extending from the line where the flaps are reflected down 
to the shoulders, and is pinned over the lower part of the 
forehead. In this manner the hair is perfectly protected from 
being soiled and ample room is left for work. 

Of the two methods of opening the skull, the circular and 
the wedge-shaped, the former makes the better museum 
preparation, but the latter is in greater use in this country, 
and has the advantage of rendering the calvarium less likely 
to slip out of place after the head has been sewed up. 

The wedge-shaped incision consists of three cuts, which 
should be outlined on the periosteum of the skull with a 
scalpel. The first cut begins just above and behind the left 
ear, and is carried over the forehead just back of the edge 
of the hair or over the frontal eminences to a corresponding 
point above and behind the right ear. The two other cuts 
begin at each end of the first incision, forming there an 
obtuse angle, and are carried back to meet in the median 
line behind at an angle of about 160 a little in front of the 
occipital protuberance. The temporal muscle on each side 
is now to be scraped back from the line of incision out of 
the way of the saw, but is not to be cut off. The holder, 
if one is used, is attached with a foot in each obtuse angle 
in the temporal region. If a holder is not employed, the 
head is best steadied by hands on the calvarium and face. 
Use towels or cloth to prevent slipping. 

Start the incision with the saw over the forehead and 
extend it back along the line marked out. It is best not to 



52 PATHOLOGICAL TECHNIQUE. 

carry the incision clear through the inner table of the bone, 
for two reasons: first, on account of the danger of injuring 
the brain-substance ; secondly, because if the inner table or 
a part of it is cracked through with a chisel and hammer, it 
can be done without injuring the underlying tissue, and the 
irregular overlapping fragments of bone thereby formed 
serve afterward for holding the calvarium firmly and steadily 
in place. 

After sawing along the lines marked out, insert a chisel in 
the frontal region, and with a quick, sharp blow crack 
through the rest of the inner table. In like manner insert 
the chisel in the middle of the other incisions and free the 
calvarium posteriorly. To remove the calvarium insert the 
chisel end of the hammer in the incision in the frontal 
region, and press down with the left hand while swinging 
the handle around in a horizontal plane. 

By means of the powerful purchase obtained the calvarium 
is easily started. Then catch the hook of the hammer over 
the calvarium and strip it off. If the dura is adherent to the 
calvarium, it may be freed by using the point of the closed 
enterotome to pry it off. 

In young children, and sometimes in old people, it is 
necessary to remove the dura with the calvarium. To do this, 
cut through the dura with the point of a scalpel along the 
lines of incision in the skull ; then cut the falx cerebri in 
the median line, both anteriorly and posteriorly. 

An infant's skull is best opened by cutting with a pair of 
scissors through the dura along the sutures (in the longi- 
tudinal suture on each side of the falx) well down to the 
floor of the skull. This gives five bone-flaps which may be 
turned out like the petals of a flower, leaving the brain unin- 
jured. It is often necessary to cut half of the base of each 
flap in a horizontal line to aid its being turned out. The 
falx cerebri must of course be divided anteriorly and drawn 
back before the brain is removed. In sewing up, the bone- 
flaps are turned in over a bag of sand or sawdust filling the 
cranial cavity, and are kept perfectly in place by the skin. 

In a case of fracture of the skull no cracking with hammer 



POST-MORTEM EXAMINATIONS 53 

and chisel is allowable ; the calvarium must be freed entirely 
by sawing. The calvarium should be examined at the time 
of removal. 

The next step is to inspect the dura. Under normal con- 
ditions it is not tense in the frontal region, but can be picked 
up with the forceps or fingers. If the dura is not thickened, 
the convolutions normally should be visible through it. The 
longitudinal sinus is opened with knife or scissors and its 
contents examined. Pacchionian granulations are not infre- 
quently found projecting into it. 

To remove the dura, cut through it with scissors or knife 
along the same lines in which the calvarium was sawn. Turn 
back each half of the dura and examine the surface of the 
convolutions and the inner surface of the dura. The con- 
volutions should be distinct and rounded, not flattened, with 
obliteration of the gyri, as occurs when there is internal 
pressure. 

The Pacchionian granulations are situated along the longi- 
tudinal fissure and may grow through the dura and form 
depressions in the calvarium. There may be apparent adhe- 
sions between the dura and pia due to veins passing from 
one to the other. The dura is still further freed by seizing 
the two halves anteriorly and lifting them up until the falx 
is tense at its insertion into the crista galli. Pass a knife in 
parallel to the falx, on the left side, with the edge forward, as 
far as the cribriform plate ; turn it to the right and cut until 
the falx yields. Withdraw the knife in the same manner in 
which it was inserted. Next draw the dura back. It is usu- 
ally more or less attached along the longitudinal fissure by 
Pacchionian granulations and by blood-vessels. These may 
be cut or torn through. Do not cut the dura posteriorly, 
but let it hang down. 

To remove tlie brain, insert the two fore fingers, or the 
first and second fingers of the left hand, anteriorly between 
the dura and the frontal lobes, one on each side of the falx 
cerebri, and draw the brain gently back until the optic nerves 
are visible. Ordinarily, the olfactory nerves come away from 
the cribriform plate without trouble, but sometimes have to 



54 



PA THOL O GICA L TE CHNIQ UE. 



be freed with the point of the knife. With a long, slender- 
bladed knife divide the optic nerves as far forward as possible 
while holding the brain back with the left hand. Continue 
to draw the brain carefully back and divide the cranial nerves 



Hypoph 



N. trigem 

N. facial. 

N. acust. 




Carotis int. 



S. cavernos. 



S. petr. inf. 
S.petr. sup. 
Cut edge 
of tento- 
rium. 



N.glossophar. 
N. vagus: 
N. recurr 



S. transfers. 
A. vertebral, 
occipit. 



Base of skull (Nauwerck). 



and the carotids. Then draw forward first the left, then the 
right temporal lobe, and cut the tentorium close to its attach- 
ment to the petrous portion of the temporal bone with a 
sawing motion, using the tip of the knife. Insert the knife 
at the side close to the squamous bone, and cut from there 



POST-MO R TEM EXAMINA TIONS. 5 5 

in toward the foramen magnum. Then cut the nerves given 
off from the medulla oblongata while supporting the con- 
vexity of the brain in the left hand. 

Lastly, carry the knife as far as possible into the spinal 
canal, and divide the cervical cord by an oblique incision 
from each side, severing the vertebral arteries with the same 
stroke. Better than a knife is the myelotome, because it 
gives a cross-section of the cord and allows more of it to be 
removed. 

The brain is now to be removed by passing the first and 
second fingers of the right hand in on either side of the cord, 
and everting the brain while still supporting it posteriorly 
with the left hand. 

Before proceeding to open the brain it is best to examine 
the base of the skull, particularly the dura, of which the 
sinuses should be incised, and the hypophysis cerebri. 

If there is a suspicion of a fracture at the base, strip off the 
dura, so as to give a better opportunity for examination of 
the bone. 

The brain should be weighed before it is dissected. The 
average weight in an adult male is 1358 grams; in an adult 
woman, 1235 grams. 

External Examination of the Brain. — Place the 
brain with the base uppermost and with the cerebellum to- 
ward the operator. Examine first the pia and the cranial 
nerves, then the arteries, especially the middle cerebral and 
its branches on each side in the fissure of Sylvius, for it is 
here that emboli most frequently lodge. The pia bridging 
the fissure of Sylvius can sometimes be torn through, but 
usually has to be cut. 

It is important, particularly in cases of obscure cerebral 
symptoms, to feel gently with the finger-tips all over the sur- 
face of the brain for any areas of increased density, because 
patches of sclerosis may in that way be found which might 
otherwise be overlooked. 

By stripping off the pia — a procedure not often advisable 
— adhesions over pathological areas can sometimes be found 
pointing to the lesions beneath, but the pia should not be 



$6 PATHOLOGICAL TECHNIQUE. 

stripped from those portions which are to be examined mi- 
croscopically. To remove the pia an incision is made on the 
median surface of each hemisphere just above the corpus 
callosum from one extremity to the other, and the pia 
stripped back first from the median and then from the con- 
vex surface. The stripping is done by means of the fingers, 
with occasional aid from the forceps. 

Section of the Brain. — There are several methods of 
cutting up the brain, no one of which is particularly suitable 
to all occasions. That method must be chosen which is most 
fitted to the individual case and to the use to which the 
tissue is to be put. 

The ideal method from a neuro-pathological standpoint 
would undoubtedly be to harden the brain entire, and then 
to make serial frontal sections thin enough for microscopical 
purposes through the whole organ. The nearest approach 
to this ideal method is to * harden the brain entire in formal- 
dehyde, a process occupying ten days to two weeks (see 
page 330), to make thin serial sections, to mordant the sec- 
tions, divided if necessary into smaller pieces, in a chrome 
salt (preferably by Weigert's quick method), and then to 
carry through a number of series from the important parts 
for microscopical examination. By this means the relations 
of the various cerebral structures and of the pathological 
lesions can be perfectly preserved and studied. This method 
can be particularly recommended for tracing degenerations 
in the motor tract. 

If there is a noticeable focal lesion, such as a tumor or 
hemorrhage, it should be so incised, generally frontally or 
horizontally, as best to show its relations to the important 
cerebral tracts and ganglia. In these cases also the best re- 
sults are obtained by hardening the brain entire in formal- 
dehyde, and later making serial sections for macroscopic 
study or for carrying through for histological purposes. In 
many cases, however, it is necessary or advisable to examine 
the lesions in the fresh state. For instance, if it be desired 
to study the neuroglia-fibers, it is positively necessary to cut 
out thin slices of fresh tissue and to fix them immediately in 



POST-MORTEM EXAMINA TIONS. 



57 



the proper solution. Often, too, the lesion cannot be or is 
not found except on fresh examination, or the clinician whose 
case it is desires to see at once the cause of certain symp- 
toms. Under such circumstances the more ideal method 
must be sacrificed, and as much made out of the case as is 
possible in the condition in which it is left after the exami- 
nation. 

For the routine examination of the brain, to demonstrate 



G.forn. G. front. I. 

G. front. II. 

G. front. III. 




G. centr. a. 

S. Rol. 

G. centr. p. 



G. marg. 
G. ang. 
inter par. 
L. par. stip. 

par. occ. 



Fig. 



C. call. 
-First cut in the brain (Nauwerck). 



its topography and to bring to light suspected or unsus- 
pected lesions, probably no method is more generally used 
than Virchow's. The objection most often made against it 
is that the cerebral cortex is too much cut up. In case, 
however, it is desired to preserve the cortex or parts of it for 
microscopic purposes, the longitudinal incisions after the first 
may be omitted, and the cortical portion, after being sepa- 
rated from the stem, may be cut in any way that seems ad- 
visable. In like manner, the brain-stem or any other part 



58 PATHOLOGICAL TECHNIQUE. 

may be left uncut, and hardened entire in formaldehyde for 
histological purposes. 

Virchow's Method. — The brain is to be placed on its base 
in the same position as one's own. Press the hemispheres 
apart a little so as to expose the corpus callosum. Hold the 
left half of the cerebrum in the left hand with the fingers on the 
lateral aspect and the thumb in the longitudinal fissure. Then 
make an almost vertical incision with a long, slender knife 
through the roof of the left ventricle in its middle third, 2 to 
3 mm. from the median raphe of the corpus callosum. The 
roof of the ventricle is to be slightly raised vertically by the 
thumb, so that the incision, which must not be too deep, may 
not injure the basal ganglia. The incision is to be continued 
into the anterior and posterior cornua. Then make a long 
incision from one end of the above cut to the other, passing 
just outside of the basal ganglia at an angle of about 45 °. 
Repeat the process on the right side, turning the brain half 
around. Next seize what remains of the corpus callosum 
and fornix in the middle, lift them, and cut through from be- 
low up, passing the knife through the foramen of Munroe. 
The parts are then turned back, exposing the velum inter- 
positum and the choroid plexuses. By drawing back the 
velum interpositum the third ventricle is uncovered. 

The corpora quadrigemina are exposed by cutting trans- 
versely the right posterior pillar of the fornix and adjoining 
brain-substance and carrying them over to the left. Each 
ventricle as it is opened is to be carefully inspected and any 
abnormal condition of its ependyma noted. The cortex is 
further divided on one side, and then on the other, by hold- 
ing it in the left hand and making vertical straight sections 
from the upper angle of the previous cut into the convex 
cortex, allowing the sections to fall apart, so as to avoid 
touching and soiling the surface with knife or fingers. Each 
portion thus cut represents a prism. The incisions should 
go well into the cortex, but not so far as to separate the 
different pieces. The basal ganglia are examined by means 
of a number of frontal sections. For this purpose the left 
hand is placed palm upward underneath the brain, so that as 



POST-MORTEM EXAMINATIONS. 



59 



each section is made over the tips of the fingers by one long 
stroke of the knife it falls forward, exposing a clean surface 
of which the two halves can be compared. An incision is 
next carried through the middle of the pineal gland, the 
corpora quadrigemina, and the vermiform process of the 
cerebellum, opening the aqueduct of Sylvius and the fourth 
ventricle. 

Each half of the cerebellum is divided by a median hori- 



Corp. call. 



Corp. call. 




Cr.forn. desc 



Cr.forn. desc. 
FIG. io. — Section of the brain (Nauwerck). 



zontal section into halves, and these portions are still further 
subdivided by a series of cuts radiating from the peduncles. 

In order to make sections of the pons and medulla the 
brain is folded together and turned over. Several cross- 
sections are then made with the left hand placed beneath as 
in sectioning the basal ganglia. 

Before making the sections it is well to remove the basilar 
and vertebral arteries, especially if they are calcified. 

In Pitre's method of dissecting the brain the lateral ven- 
tricles are opened as in Virchow's method. Then the pedun- 
culi cerebri are cut squarely across, so as to remove the pons 



6o PATHOLOGICAL TECHNIQUE. 

and cerebellum, and a longitudinal incision is carried down 
through the third ventricle, halving the cerebrum. Through 
each half of the cerebrum a series of six sections is then 
made parallel to the fissure of Rolando. The names of the 
sections and the important parts which they show are as 
follows : 

1. The pre-frontal section through the frontal lobe, 5 cm. 
anterior to the fissure of Rolando, shows the gray and white 
substance of the frontal convolutions. 

2. The pediculo -frontal section through the posterior por- 
tions of the three frontal convolutions shows the anterior 
extremity of the island of Reil, the lenticular and caudate 
nuclei, and the internal capsule. 

3. The frontal section through the ascending frontal con- 
volution, parallel to the fissure of Rolando, shows the optic 
thalamus, the lenticular and caudate nuclei, the claustrum, 
the external and internal capsules, the anterior portion of the 
descending horn of the lateral ventricle, and the island of 
Reil. 

4. The parietal section through the ascending parietal con- 
volution shows portions of the same structures as the pre- 
ceding, and a transverse view of the hippocampus. 

5. The pedicido-parietal section through the parietal lobe, 
3 cm. posterior to the fissure of Rolando, shows the tail of 
the caudate nucleus in two places and the posterior portion 
of the optic thalamus. 

6. The occipital section through the occipital lobe, I cm. 
in front of the parieto-occipital sulcus, shows simply the 
white and gray matter of the occipital lobe. The cere- 
bellum, pons, and medulla are incised in the manner already 
described. 

Removal of the Spinal Cord. — The body is to be 
placed face downward, with the head over the end of the 
table and a block under the chest. The incision is made 
over the spinous processes from the occiput to the sacrum. 
Dissect the skin and muscles back on each side, so as to 
leave the vertebral laminae as bare as possible. The laminae 
may be cut through by means of several instruments, of 



POST-MORTEM EXAMINATIONS. 6 1 

which the double-bladed saw (Luer's rhachiotome) is perhaps 
the safest, at least for beginners. The single-bladed saw 
with rounded end is also very useful and can be thoroughly 
recommended. The operation can be done most quickly by 
biting off the spinous processes with the heavy bone-forceps 
and cutting through the laminae with chisel and hammer, 
but there is greater danger of injuring the cord. 

The numerous artifacts in the cord, reported as neuromata 
and heteroplasia even within very recent times by competent 
pathologists, would seem to indicate that the need of careful 
and delicate technique in the removal of the spinal cord is 
not yet fully appreciated. 

The laminae should be sawn nearly or entirely through in 
a line with the roots of the transverse processes from the 
third or fourth lumbar vertebra to the cervical region. The 
arches of the cervical vertebrae are best divided with a heavy 
bone-cutter, because they cannot be easily sawn, and there 
is sufficient room here for the points of the bone-cutter with- 
out danger of their pressing on the cord. 

It is important to strike the outside limits of the spinal 
canal, so as to get as much room as possible for the removal 
of the cord. Test if the sawing be deep enough by the 
mobility of the spinous processes. If necessary, they can 
be freed by means of the hatchet-chisel and a hammer in 
the same way that the calvaria is loosened. 

As the cord reaches only to the second lumbar vertebra, 
cut through between the third and fourth, free with the 
heavy bone-cutter the lower end of the row of the spinous 
processes, which are held together by their ligaments, and 
strip them up to the neck ; then cut through the cervical 
arches with the bone-cutter, taking care that the point 
within the canal does not come in contact with the cord. 

The nerve-roots are to be divided with a sharp scalpel by 
means of a long cut on each side of the cord. Then cut 
across the dura and the nerve-roots at the lower end of the 
exposed canal, and, while holding the dura with forceps, 
carefully free the cord from below up with scissors or scalpel, 
taking care all the time not to pull or bend the cord, be- 



62 



PA THO L O GICA L TE CHNIQ UE. 



cause in either way artifacts may be produced. Cut the cord 
squarely across as high in the cervical canal as possible, so 
that the remaining portion may be easily removed with the 
brain. 

Lay the the cord after removal on a flat surface and incise 
the dura longitudinally, first posteriorly and then in front. 
A series of cross-sections, usually I to 2 cm. apart, is made 
through the cord while supported on the fingers during the 




Fig. ii. 



-Base of skull, showing lines of incision for removing internal eye, etc. 
(Nauwerck). 



cutting, so that the cut surfaces shall fall apart. The dif- 
ferent segments should ordinarily be left attached to the 
dura, so that their position in the cord can easily be deter- 
mined. 

A diagnosis from the fresh, macroscopic appearances of 
the cord is often very difficult to make, according to the best 
authorities. 

The Eye. — The contents of the orbit, including the poste- 
rior part of the eye, can be readily examined by chiselling 



POST-MORTEM EXAMINATIONS. 63 

off the roof of the orbit. The posterior half of the eye can 
be removed by cutting around the eyeball with sharp scissors 
without changing the hold of the forceps on the sclera. If 
done quickly, the retina remains quite well spread out. The 
anterior half of the eyeball is to be propped in place by a 
plug of cotton dipped in ink or in a solution of perman- 
ganate of potassium. 

The Ear. — The middle ear can be exposed by chipping 
off with a chisel its roof, which lies in the middle of the 
petrous portion of the temporal bone. The roof can also 
be very easily bitten off with the heavy bone-cutters. If, how- 
ever, it be desired to examine the ear more carefully by 
means of a section through the external meatus and the 
middle ear, it will be necessary to remove the whole of the 
petrous bone. For this purpose the incision behind the ear 
must be carried back along the anterior edge of the trapezius 
muscle halfway down the neck. Then the skin-flaps, in- 
cluding the external ear and the underlying tissues, must be 
dissected back for some distance on each side of the incis- 
ion. Two converging incisions are then to be sawn, the 
anterior passing through the root of the zygomatic arch, 
the posterior just back of the sigmoid sinus, so as to come 
together at the apex of the pyramid of the petrous bone, or, 
better still, to meet in the foramen magnum. An ordinary 
chisel and a hammer or mallet will be found very convenient 
for freeing the petrous bone after the incisions have been 
sawn. 

In the examination of the petrous bone after it has been 
removed the first step is to chisel off the tegmen tympani so 
as to get a view of the middle ear. Next remove the lower 
wall of the external meatus, so as to expose the outer sur- 
face of the membrana tympani. Finally divide the petrous 
bone with a fine hair-saw by an incision starting in at the 
styloid process and coming out at the carotid canal, parallel 
to the crest of the pyramid of the petrous bone. 

This incision divides the cavum tympani into halves. In 
the lateral half can be seen the membrana tympani with the 
hammer and the anterior half of the mastoid cells. In the 



64 PATHOLOGICAL TECHNIQUE. 

median half are the labyrinthine wall of the cavum tympani 
with the stapes and the posterior half of the mastoid cells. 
It is best to remove the anvil before sawing through the 
bone. The Eustachian tube can be easily exposed by start- 
ing from its termination in the middle ear. 

The Naso -pharynx. — Although a fair view of the nares 
and pharynx can be obtained by chiselling off the portion 
of the base of the skull lying over them, the method does 
not begin to offer the satisfactory view that can be obtained 
by the method of Harke, 1 a method which is not so difficult 
as might at first sight seem, and which consists in halving the 
base of the skull by a longitudinal incision. To do this the 
original incision in the scalp must be extended on each side 
over the mastoid processes and along the anterior edge of 
the trapezius muscle to a point below the middle of the neck. 
Then the posterior flap and the underlying muscles must be 
freed from the occipital bone and the upper portion of the 
cervical vertebrae. In like manner, the anterior flap must 
be dissected from over the root of the nose and the upper 
edge of the orbits, and be drawn down over the face. Then 
flex the head strongly forward and saw through the occipital 
bone and the base of the skull, dividing the occipital and 
frontal bones, the sella turcica, the cribriform plate, and the 
basilar process into equal halves. Anteriorly, it is well to 
go a little to the left or right, so as not to injure the nasal 
septum. 

The next step is to cut the pachymeninx and the appara- 
tus ligamentosis between the anterior edge of the foramen 
occipitale magnum and the processus odontoideus, as well 
as the inner side of the atlanto-occipital joint from within. 
Then the two halves of the skull are to be drawn forcibly 
apart. The nasal bones, the hard palate, and the alveolar 
process of the upper jaw break, and the two halves of the 
base of the skull open like a book, revolving around an axis 
which passes through the joint of the lower jaw and the 
atlanto-occipital joint. 

If the foramen occipitale magnum offer too muph resist- 

1 Berliner klin. Woe hens chrift, 1 892, No. 30. 



POST-MORTEM EXAMINATIONS. 6$ 

ance, break through it with a chisel, and also if necessary 
through the anterior and posterior arches of the atlas. 

It is now easily possible to inspect the sinus sphenoidales, 
the nasal septum, the frontal sinuses, and the nasal passages. 
The antrum of Highmore is easily opened with forceps and 
a pair of bone-shears. 

After the operation the two halves of the base of the skull 
are brought together, and wired if necessary. When the 
skin-flaps have been replaced all evidence of the operation is 
covered up. 

Examination of New-born and Very Young Chil- 
dren. — i. The head is preferably opened by the method given 
on page 52. 

2. According to Nauwerck, the spinal canal can be opened 
by dividing the vertebral arches with strong scissors. 

3. The umbilical cord, if present, and the umbilical arte- 
ries demand close attention in children who have lived a few 
days or weeks, for the purpose of determining if infection has 
taken place at that point. Nauwerck advises a modification 
of the primary long incision. A little above the umbilicus 
it should divide into two diverging incisions running to the 
pubes. In this way a triangular flap is left containing the 
umbilical arteries, while from the upper end is given off the 
umbilical vein. The vessels may be ligated or opened at 
any point that seems advisable. 

4. Anomalies of circulation should be looked for in all 
" blue babies." The closure or non-closure of the ductus 
Botalli (arteriosus) is best determined in situ by dissecting 
off the thymus and opening up the pulmonary vein in the 
middle of its anterior surface. The cut may be extended 
downward, if desired, through the pulmonary valve and the 
wall of the right ventricle. The duct lies in the median line 
of the pulmonary artery, a little above its division into its 
two main branches. A small probe can be passed through 
it into the aorta. The condition of the foramen ovale be- 
tween the auricles is easily examined. 

For other anomalies of the circulation it will usually be 
found most satisfactory to remove the thoracic organs in 
5 



66 PATHOLOGICAL TECHNIQUE. 

mass, so as to be able to open up the heart and the vessels 
given off from it before any of the vessels have been severed 
from their connections. 

5. In medico-legal cases especially it is important to de- 
termine whether or not a child has breathed. The main 
steps of the process are as follows : 

(a) Position of the diaphragm before the chest is opened. 
When the lungs are fully distended it is at the fifth or sixth 
rib on the right and at the sixth rib on the left. When the 
lungs contain no air or are but partially distended the 
diaphragm reaches to the fourth rib. 

(b) Ligate the trachea above the sternum before opening 
the thorax. 

{c) After examining the heart, etc., divide the trachea above 
the ligature and remove the thoracic organs in one piece. 

(d) Dissect off the thymus gland and the heart, and place 
the lungs in a large dish of clear cold water to see if they 
will float or not. 

(e) Incise the lungs and notice if they crepitate ; squeeze 
the lung-tissue gently, and see if bubbles of air mingle with 
the blood on the surface, or squeeze the lung beneath water 
and observe if bubbles of air rise to the surface. Decompo- 
sition may give rise to gas in the lungs. 

(/) Divide the lungs into lobes, and then into small 
pieces, and determine if any of them will float. 

Table of the Weight and Length of the Fetus at each Month 
of Gestation (from v. Hecker, cited by Nauwerck). 



Time in months. 


Weight. 


Length. 


2 


4gr. 


2.5-3 cm, 


3 


5-20 " 


7-9 " 


4 


120 " 


10-17 " 


5 


284 " 


18-27 " 


6 


434 " 


28-34 " 


7 


1218 « 


35-38 " 


8 


1549 " 


39-41 " 


9 


1971 " 


42-44 " 


10 


2334 " 


45-47 " 



6. The long bones should be incised, so as to expose the 



POST-MORTEM EXAMINATIONS. 6j 

epiphyseal line, which should be examined for evidences of 
congenital syphilis. The ends of the femur and tibia at the 
knee are usually chosen. For making the incision a fine 
hair-saw is preferable to a knife, because the latter often 
causes the bone to break apart at the epiphyseal line. 

The age of the fetus in months can be determined after 
the fifth month by dividing the length in cm. by 5. 

Weight of Organs in a New-born Child. 

Brain 380 gr. (Bischoff). 

Thymus 14 « (Friedleben). 

Heart 20.6 " (Thoma). 

Lungs 58 " 

Spleen 11.1 " 

Kidneys together 23.6 " (Thoma). 

Testicles 8 " 

Liver 118 " 

Restitution of the Body. — After an autopsy is finished 
it is necessary to put the body into such a condition that no 
evidence of the operation will be noticed except on careful 
inspection. All fluids should be removed from the cavities. 
Organs not required for further examination should be re- 
placed. The brain is placed in the body-cavity because it is 
usually impossible to restore it to the skull. The best mate- 
rial for filling up the cavities is fine sawdust. It packs easily 
and smoothly, absorbs well, keeps the needle dry so that it 
does not slip, and does not interfere with sewing like oakum, 
which gets into the stitches. In private autopsies any make- 
shift, such as bran, newspapers, or cloth, must be employed. 
If the pelvic organs have been removed, stuff the pelvis 
tightly to prevent leakage. The cranium may be left empty, 
although it is usually better to pack a little sawdust or other 
material into the base of the skull and the upper part of the 
spinal canal to prevent leaking. Sometimes it is advisable to 
fill the cranial cavity with sand or sawdust wrapped tightly 
in a cloth, of which the edges are brought together and 
twisted so as to crowd the material into a compact mass. If 
the thoracic cavity is well packed with sawdust, the sternum 
will stay perfectly in place without being sewed. 



6& PATHOLOGICAL TECHNIQUE. 

If part of the vertebral column has been removed, a stick 
or heavy iron rod should be run into the spinal canal above 
and below, so as to stiffen the body and hold it in position 
while it is filled about half full of plaster of Paris. After 
this has set there is little danger of the body losing its form. 

In sewing up the body-cavity, begin at the neck. Use a 
piece of twine a little over one and a half times the length 
of the incision. Take one stitch and fasten the end with a 
simple knot or with a surgeon's knot. Turn the loose end 
in under the skin. Hold the attached end of the twine taut 
with the left hand about 8 to 10 cm. from the line of incis- 
ion. The needle is then passed from within outward through 
the edge of the flap and in a diagonal line from below up- 
ward. The stitches should be from I to 2 cm. apart, and 
about the same distance from the edge of the flap. The ob- 
ject of keeping the end of the twine taut is to keep the 
sutures tight and the edges of the flaps up so that the needle 
can be thrust in easily. 

Arrived at the lower end of the incision, take two button- 
hole stitches and draw them tight. Then take a long stitch 
off to one side and cut the twine close to the skin, so as to 
bury the end of it deeply and securely. 

If in removing the calvarium the precaution is taken to 
crack at least a part of the inner table with the chisel and 
hammer, projecting pieces of bone are usually left which 
interlock and hold the calvarium snugly in position when 
it is replaced. It is further fastened by sutures on each side 
through the fascia of the temporal muscle. It is always 
more difficult to sew up the incision in the scalp than the 
one in the body, especially when the hair is long. Care 
should be taken to bury the ends of the suture securely. 

The skull of a child is so thin that it is usually best to 
wire the calvarium in place or fasten it by means of double 
tacks, otherwise it may slip out of place after the scalp has 
been sewed up. 

Slee's ingenious method deserves mention. The usual 
saw-cuts in the skull over the ear are allowed to cross each 
other, so that slits about an inch long are formed in the tern- 



POST-MORTEM EXAMINATIONS. 69 

poral bone. An ordinary roller bandage is stretched across 
the skull and crowded edgewise into the slits. Then the cal- 
varium is replaced and the ends of the bandage are tightly 
overlapped over the vertex and secured by pins. 



PART II. 
BACTERIOLOGICAL METHODS. 



I. CULTURE=MEDIA. 



Culture-media consist of various nutritive substances, 
either liquid or solid, in or upon which bacteria will grow 
and multiply, and are, as a rule, contained in test-tubes ready 
for use. 

The nutritive material in these test-tubes must be free from 
living bacteria — i. e. " sterile " — and must be kept so until 
used. This is accomplished by inserting a stopper of raw 
cotton into the mouth of each test-tube to exclude the en- 
trance of bacteria from without, and then subjecting the 
tubes and their contents to the sterilizing action of live 
steam for the purpose of killing any bacteria which may 
have gained access to the medium during its preparation. 

The Preparation of Test-tubes. 1 — New test-tubes 
should be washed in a very dilute solution of nitric acid 
(2—5 c.c. of the commercial nitric acid to the liter of water), 
then thoroughly rinsed in water and allowed to drain until 
dry or nearly so. The object of the use of the nitric acid is 
to remove any free alkali which may be present in the new 
tubes. 

Old test-tubes containing culture-media, after removal 
of the cotton stoppers, should be boiled for from half an 
hour to one hour in a solution of common soda (4-6 per 
cent.). This treatment not only destroys bacteria, but it also 
loosens and liquefies the material in the tubes, so that it may 
be easily removed with the aid of a test-tube brush and 
plenty of water. 

1 Test-tubes of the size known as 6 x 3^ in. are recommended. 
70 



BACTERIOLOGICAL METHODS. J l 

When all the material has been removed from the test- 
tubes in this way, they are to be rinsed in clean water, then 
in the dilute nitric acid of the strength above indicated for 
the new test-tubes, and finally again rinsed in clean water, 
after which they are to be allowed to drain until dry or 
nearly so. 

The test-tubes thus prepared are next to be provided with 
stoppers of raw cotton (not absorbent cotton), which are to be 
inserted into the mouths of the tubes for a distance of about 
3 cm., and should fit the walls of the tubes smoothly. The 
stoppers should not be packed in nor fit too tightly, but be 
just firm enough in position to easily sustain the weight of 
the tube when it is lifted by the projecting portion of the 
cotton. 

The stoppered tubes are then to be packed into a square 
wire basket which fits into the hot-air sterilizer, 1 and heated 
in this, with the door closed, until the temperature reaches 
about 150 C. The object of this heating is not to sterilize 
the tubes and cotton stoppers, but to mould the stoppers to 
the shape of the test-tubes, so that they can readily be re- 
placed when removed in the subsequent filling of the tube 
with nutritive material. In packing the tubes into the square 
wire basket as many as possible should be placed with the 
cotton stopper uppermost, and the remainder of the space in 
the basket above the tubes may be filled with tubes placed 
on their sides. 

PREPARATION OF CULTURE=MEDIA. 

Bouillon. — Formula for 1000 c.c. : 

Lean beef, 500 grams ; 

Or extract of beef, 3 " 

Pepton, 10 " 

Sodium chlorid, 5 " 

Water, 1000 c.c. 

500 grams, or about I \ pounds, of lean beef, finely minced, 
are thoroughly mixed with 1000 c.c. of ordinary tap-water 

1 See any dealer's catalogue of bacteriological apparatus. 



*]2 PATHOLOGICAL TECHNIQUE. 

and the mixture is then boiled in a saucepan over the gas 
stove 1 for about half an hour. It is next filtered through 
filter-paper to obtain the clear infusion of the beef, free from 
the coagulated albumin and shreds of tissue. This clear 
beef-infusion is then turned back into the saucepan, which 
should be clean, and to it are added 10 grams of pepton 
(Witte), 5 grams of sodium chlorid, and sufficient water to 
make the total volume of the mixture iooo c.c. The volume 
of iooo c.c. may be indicated with sufficient accuracy by a 
mark previously made on the inner surface of the side of the 
saucepan. The mixture is next to be boiled until all these 
substances are dissolved, stirring frequently with a glass rod, 
and is then to be neutralized, for it has a decidedly acid 
reaction from the acid of the meat. 

The neutralization is important and requires care (see also 
p. 83). The reaction required is that of a very faint alka- 
linity, as is shown by the production of a blue color on red 
litmus paper, while no change is produced on the blue 
litmus paper. In neutralizing, a 10 per cent, solution of 
caustic soda is added, a few c.c. at a time at first, and later, 
two or three drops at a time, while the mixture is kept boil- 
ing, the reaction being tested between each addition of alkali 
after thorough stirring with a glass rod. 

The test of the reaction is best made by placing a drop of 
the mixture on a piece of litmus-paper by means of the 
glass rod and then moistening the paper at the water-faucet. 
In this way the best judgment can be formed of changes in 
the color of the paper. If the mixture becomes too alkaline, 
dilute hydrochloric acid is to be added to correct this. 

When the proper reaction has been obtained the mixture 
is to be filtered through filter-paper into a flask, and suf- 
ficient water added to bring the volume of the filtrate up to 
iooo c.c, thus replacing the loss by evaporation. The fil- 
trate in the flask is now bouillon. If the bouillon be heated 
to the boiling-point, it will usually become more or less 

1 In the preparation of culture-media some form of gas stove is preferable to 
a Bunsen burner. 



BACTERIOLOGICAL METHODS. 73 

clouded by a precipitate of phosphates. As a rule, subse- 
quent heatings do not cause any further precipitations. 
Therefore it is advisable, if it is desired to obtain perfectly 
clear bouillon, to steam the flask containing the freshly pre- 
pared bouillon in the steam sterilizer for about half an hour, 
and then, if the bouillon be clouded, to again filter, so that 
the subsequent sterilizations in the test-tubes will not cause 
precipitates. 

The finely minced beef may be obtained in the shops 
under the name of Hamburg steak, or it may be very readily 
prepared with the aid of a meat-grinder. 

The usual directions for the preparation of bouillon require 
that the mixture of the minced meat and water be allowed 

a 

to stand over night in a cool place before boiling. In our 
experience this is not necessary. 

For bouillon cultures the bouillon is run into test-tubes, 
each tube being filled to a depth of about 4 cm., and steril- 
ized immediately and on the two following days, according 
to the general directions given on page 87, after which it is 
ready for use. 

Bouillon may also be made as above indicated by using 
three grams of Liebig's extract of beef to the liter, instead 
of the beef-infusion. 

Glucose Bouillon. — Formula : 



Glucose (dry), 
Lean beef, 

Or extract of beef, 
Pepton, 
Sodium chlorid, 


10 grams 
500 

3 " 
10 " 

5 " 


Water, 


IOOO c.c. 



This medium is identical with the preceding, except that it 
contains 10 grams of glucose to the liter (1 per cent.) in ad- 
dition to the other ingredients. The preparation of glucose 
bouillon is the same as that of plain bouillon, the glucose 
being added with the pepton and sodium chlorid. 



74 PATHOLOGICAL TECHNIQUE. 

Agar-agar (plain). — Formula for iooo c.c. : 



Agar-agar, 


15 grams; 


Lean beef, 


500 


Or extract of beef, 


3 " 


Pepton, 


10 


Sodium chlorid, 


5 " 


Water, 


1000 c.c. 



Agar-agar is essentially bouillon in which agar-agar "has 
been dissolved so that a transparent jelly is formed. The 
function of the agar-agar is merely to give the medium the 
property of becoming liquid when heated and solid when 
cool ; it is not nutritive. The nutritive substances are in the 
bouillon. 

To make one liter, 15 grams of agar-agar are placed in 
the clear beef-infusion, made as described on p. 71 and 
boiled for one hour in a saucepan. 1 The agar-agar dissolves 
slowly, and continuous boiling is necessary to ensure its 
subsequent nitration. Before boiling, about 200 c.c. of water 
should be added to compensate for evaporation, and later, as 
the level of the liquid falls, more water should be added 
from time to time. It is well to have some mark on the side 
of the saucepan which will indicate the level of a liter. 
When the boiling is nearly finished, 10 grams of pepton, 5 
grams of sodium chlorid, and sufficient water to make a 
volume of one liter are added to the mixture. The mixture 
is then neutralized, as described for bouillon, while still boiling. 

After the boiling is completed the saucepan is to be placed 
in cold water until the temperature of its contents falls 
to about 6o° C, as shown by the thermometer, the cooling 

1 If an autoclave (see p. 88) be available, it may be used very conveniently 
in hastening the solution of agar-agar in the meat-infusion. For this purpose 
the mixture of finely fragmented agar-agar and the beef-infusion should be 
placed in a Florence flask. When the temperature of the interior of the auto- 
clave has reached about 120 C. or when the gauge shows a pressure of 
two atmospheres, the heat should be turned off and the apparatus allowed to 
cool to about ioo° C. before opening. The mixture is then transferred to a 
saucepan and the preparation proceeded with as above indicated. 



BACTERIOLOGICAL METHODS. 



75 



being facilitated by stirring with a glass rod. When this 
temperature is reached, an egg is beaten into the mass and 
the saucepan with its contents replaced on the stove, where 
it is slowly brought to boiling and boiled for about ten min- 
utes. The object of the adding of the egg is to clarify the 
medium. It is then filtered, boiling hot, through wet folded 
filter-paper into a flask. A funnel with corrugations on its 
sides is best to use. With this the folding of the filter-paper 
is not necessary. 

In order to save time, it is best to use two filters and two 
flasks at once, for the filtration rapidly becomes slow as the 
mass cools, and several heatings of the residue on the filter 
are necessary. As soon as the fil- 
trate begins to appear slowly, drop 
by drop, the mass remaining on 
the filter should be turned back 
into the saucepan — which can best 
be done by making a hole in the 
bottom of the filter with the glass 
rod — and brought again to boiling. 
While boiling hot it is again poured 
on a fresh filter. This preparation 
of fresh filters and reheating may 
have to be repeated several times 
before all of the mixture is filtered. 
The filtration may also be carried 
on in the steam sterilizer to pre- 
vent the cooling of the medium. 

When the amount of coagulated 
egg-albumin and medium remain- 
ing on the filter does not exceed a 
volume of 50-100 c.c, the filtra- 
tion may be considered complete. 
To the filtrate, which is now agar- 
agar, is next added sufficient water 
to make up the loss by evaporation, 
and the medium is then to be run 
into test-tubes and sterilized, as described on page S". 




Fig. 



:2. — " Stab " culture (a) ; 
' slant " culture (6). 



y6 PATHOLOGICAL TECHNIQUE. 

In view of the difficulty of filtering agar-agar, it has been 
proposed to avoid this operation by placing the fluid medium 
in a sedimenting vessel, such as a large funnel, with closed 
apex. The solid particles settle to the bottom if the medium 
be maintained in a fluid condition in the steam sterilizer for 
a certain length of time. When the medium has become 
solid it is turned out of the vessel as a cast, and the bottom 
portions, containing the sediment, cut off from it and rejected. 
The remaining portion will be found clear enough for most 
purposes and may be melted up at once for distribution in 
tubes, or if it now be desirable to further clarify it, it may be 
melted up and filtered as described above. It will be found 
to filter more readily than before. 

Precipitates of phosphates in the medium frequently occur 
after the first sterilization, but if these be removed they do 
not usually appear again in subsequent heatings. Therefore, 
if it be desirable to obtain a very clear agar-agar, it is well to 
place the flask containing the freshly-prepared medium in 
the steam sterilizer for half an hour, and then filter again to 
remove any precipitate which may have appeared. The 
subsequent sterilization in the test-tubes will then cause no 
precipitation. 

In filling the test-tubes it is customary to fill some tubes 
to a depth of about 3 cm. and others to a depth of about 5 
cm. After the complete sterilization of the medium in the 
tubes as described on page 87, the first-mentioned tubes are 
placed on their sides with their mouths slightly elevated 
while the medium is still fluid, so as to form, after solidification, 
a slanting surface extending from near the bottom of one 
side of the tube to about half the length of the tube on the 
opposite side. The solidification of the agar-agar takes place 
in a short time, and as soon as it occurs the tubes are ready 
for use, this form of culture being known as a " slant " tube 
or culture (Fig. 12, b). It is well, however, to allow the 
tubes to remain in their slanting position for a day or two to 
permit the medium to become more or less adherent to the 
walls of the tube, and thus avoid its tendency to slide down- 
ward when the tubes are placed in the upright position. 



BACTERIOLOGICAL METHODS. j "J 

The tubes filled to a depth of 5 cm. are to be allowed to 
cool and solidfy while in an upright position, and the form 
of culture-tube thus obtained is called a " stab " culture (Fig. 
12, a), because the medium in the tube is inoculated for cul- 
ture purposes by inserting an infected platinum wire into its 
depths. 

Glucose Agar-agar. — Formula for 1000 c.c. : 

Glucose (dry), ic grams . 

Agar-agar, 1 5 

Lean beef, 500 " 

Or extract of beef, 3 " 

Pepton, 10 " 

Sodium chlorid, 5 " 

Water, 1000 c.c. 

This medium differs from plain agar-agar only in the addi- 
tion of 10 grams (1 per cent.) of glucose. The glucose 
should be obtained in the form of solid masses, not as a thick 
fluid, and it is to be added with the pepton and sodium 
chlorid. In short, glucose agar-agar is made with glucose 
bouillon in identically the same manner that plain agar-agar 
is made with plain bouillon. 

Lactose-litmus agar- agar consists of plain agar-agar to which 
has been added 2 or 3 per cent, of lactose and sufficient litmus 
tincture to give it a pale-blue color. 

Glycerin Agar-agar. — Formula for 1000 c.c. : 



Glycerin, c. p., 


60 c.c. ; 


Agar-agar, 


15 " 


Lean beef, 


500 grams ; 


Or extract of beef, 


3 " 


Pepton, 


10 . " 


Sodium chlorid, 


5 " 


Water, 


IOOO c.c. 



This medium is prepared by adding to plain agar-agar after 
its final filtration, and before running it into the test-tubes, 60 
c.c. (6 per cent.) of glycerin c. p., and mixing thoroughly. 



7 8 PATHOLOGICAL TECHNIQUE. 



Gelatin (plain). — Formula for 


iooo c.c. : 


Gelatin, 


IOO grams ; 


Lean beef, 


500 


Or extract of beef, 


3 " 


Pepton, 


10 " 


Sodium chlorid, 


5 " 


Water, 


1000 c.c. 



Gelatin is essentially bouillon in which gelatin has been 
dissolved, so that a transparent jelly is produced which is 
solid at ordinary temperatures and fluid when slightly 
warmed. To prepare one liter, 100 grams (10 per cent.) 
of golden seal French gelatin are dissolved in a liter of the 
hot bouillon which has been heated to boiling in a saucepan. 
When the gelatin is thoroughly dissolved the mixture is 
boiled for about five minutes, and the marked acidity of the 
gelatin then carefully neutralized by the addition of caustic 
soda, in 10 per cent, solution, to a very faint alkalinity, as 
has been described in the preparation of bouillon. As in 
the case of agar-agar, the mass is then cooled to 6o° C, an 
egg beaten into it, then gently heated again to boiling, and 
boiled about ten minutes, when it is to be filtered through a 
wet folded filter into a flask. Gelatin usually filters fairly 
rapidly, but time may be saved by using two filters at once. 
When filtered it is to be run into test-tubes and sterilized, 
as described on page 87. It is used both in the form of 
" slant " and " stab " cultures, as in the case of agar-agar 
(see page 76). 

In the preparation of this medium it is important to sub- 
ject it as little as possible to the boiling temperature, for 
prolonged exposure to this destroys its power of solidifying. 
Therefore in sterilizing, gelatin tubes should never be allowed 
to remain exposed to live steam longer than twenty minutes. 
It is also important to apply the heat slowly during the pro- 
cess of heating after the addition of the egg above mentioned, 
in order to avoid " burning." 



BACTERIOLOGICAL METHODS. J 9 

Glucose Gelatin. — Formula for iooo c.c. : 



Glucose, 
Gelatin, 


10 grams; 
IOO " 


Lean beef, 

Or extract of beef, 
Pepton, 
Sodium chlorid, 


500 

3 " 
10 " 

5 " 


Water, 


1000 c.cm. 



This medium is essentially gelatin dissolved in glucose 
bouillon (see page 73), and is prepared in the same manner 
as the plain gelatin, except that glucose bouillon is used in- 
stead of plain bouillon. 

Blood-serum (Loffler's Mixture). — Formula : 

Glucose bouillon (see page 73), I part ; 
Beef blood-serum, 3 parts. 

This culture-medium consists of a mixture of the blood- 
serum of the bullock and glucose bouillon, which is run 
into test-tubes and coagulated by heat in such a way as to 
form a slanting surface for culture purposes — i. e. it is used 
in the form of " slants." 

The blood-serum is collected at the slaughter-house in 
tall glass jars of the capacity of a gallon or more. These 
jars should be thoroughly clean, but sterilization is not 
necessary. 

The blood which is obtained by the Jewish method of 
slaughter — viz. by severing the carotid artery — is the best for 
the purpose, because it clots more readily. As the blood 
runs from the vessels of the animal it is received in the glass 
jar, and immediately placed in a cool place for twenty-four 
to forty-eight hours to allow it to clot and the serum to 
separate. All unnecessary agitation of the fresh blood 
should be avoided, as this interferes with its proper clotting. 
It is well to inspect the blood after a few hours, and gently 
loosen with a clean glass rod any adhesions which the clot 
may have formed to the wall of the jar, thus allowing the 
clot to more readily contract and squeeze out the serum 



8o PATHOLOGICAL TECHNIQUE. 

from its meshes. After about twenty-four hours the serum 
is removed by the aid of a clean pipette and brought to the 
laboratory. If the clot is in good condition, more serum will 
appear after another twenty-four hours, and if necessary this 
also may be used. 

The presence of red blood-corpuscles in the serum is of 
little importance. Three parts of the beef blood-serum thus 
obtained are to be thoroughly mixed with one part of glucose 
bouillon {vide supra), convenient quantities being 900 c.c. of 
blood-serum and 300 c.c. of glucose bouillon. 

This mixture is then run into test-tubes as described on 
page 85. The quantity run into each test-tube should be 
sufficient to fill it to a depth of about 3-4 cm. The tubes 
containing the requisite amount of the mixture are next 
subjected to the action of heat while in a slanting posi- 
tion, so that the mixture in the tubes may become solid 
or coagulated, and so offer a smooth slanting surface for 
culture purposes extending from a point near the bot- 
tom of the tube to about halfway up the opposite side or 
higher. 

The coagulation is effected either in the hot-air sterilizer 
by packing the tubes on their sides, the proper slant being 
secured by means of strips of cardboard placed between the 
layers of tubes, or better, in the blood-serum coagulator 
which may be obtained from dealers in bacteriological 
apparatus. 

If the hot-air sterilizer is employed, the temperature should 
not exceed 90 C. nor fall below 85 ° C, and the door should 
be kept closed. It is optional whether the sterilizer be 
packed full of tubes or only a few layers of tubes be coagu- 
lated at a time, with careful watching to avoid overheating. 
In the former case two or three hours will be required to 
firmly coagulate the tubes in the middle layers, while the 
lower layers may be overheated. To avoid this overheating 
of the lower layers, a false bottom or one or two layers of 
empty tubes may be employed. 

The blood-serum coagulator is much more convenient 
and gives much more satisfactory results. The temperature 



BACTERIOLOGICAL METHODS. 8 1 

of the interior should be kept at about 95 ° C. To save 
time in heating, the apparatus may be filled with hot water 
from the hot-water faucet. 

Whichever apparatus is employed for coagulation, it is of 
the utmost importance that the coagulation of the mixture 
be a thorough one, and that the medium in the tubes becomes 
firm and solid, otherwise bubbles and cavities will form in it 
and destroy its smooth surface when it is subjected to the 
subsequent steam sterilization. When the tubes are firmly 
coagulated they are to be packed with the cotton stopper 
uppermost in a round wire basket and sterilized by steam 
three times, as indicated on page 87, after which they are 
ready for use. 

This method of preparing blood-serum tubes is very 
different from the one usually described, a most tedious 
and time-consuming procedure, requiring a high degree 
of technical skill, by which it is practically impossible 
to make use of blood-serum tubes for ordinary pur- 
poses. 

With the method here detailed we think that the best cul- 
ture-medium for the routine examination of pathological 
material is obtained. It is preferred by us for various 
reasons, chief of which are as follows : 

First, the ease and facility with which it can be prepared, 
especially when a proper coagulating apparatus is available. 

Secondly, the greater and more rapid growth of certain 
important pathogenic bacteria upon it than upon ordinary 
media. 

In the method usually described the serum (which should be 
clear or free from blood-corpuscles) is obtained under all aseptic 
precautions, is carefully mixed with sterile glucose bouillon in the 
proportions given above, and the mixture then run into sterile 
test-tubes. During all the manipulations precautions are neces- 
sary to avoid contamination, the serum never being allowed to 
come in contact with any object which is not sterile, and exposure 
to the air during the processes of transference from one vessel to 
another avoided as much as possible. 

The mixture now being in test-tubes, it is subjected for one 
hour on each of five successive days to a temperature of 6S° to 
70 C. in a chamber provided with a water-jacket. This tern- 



82 PATHOLOGICAL TECHNIQUE. 

perature is sufficient to kill the vegetative forms of any bacteria 
which may be in it, but does not coagulate the medium. The 
intervals between the sterilizations are for the purpose of allowing 
any spores to develop into the vegetative form and thus become 
susceptible to the destructive action of heat. 

After the fifth sterilization the medium is solidified in the tubes 
in the form of " slants " by slowly raising the temperature of the 
chamber to about 8o° C, and keeping the tubes at this tempera- 
ture for several hours. In solidifying the great object is to obtain 
a gelatin-like, fairly transparent medium and to prevent opacity. 
To attain this it is necessary to proceed very carefully with the 
heating and avoid overheating or too rapid heating, the tubes 
being inspected from time to time and removed from the chamber 
as soon as their contents have the proper consistency. When 
gelatinized the tubes are placed in the incubator for twenty -four 
hours to determine whether they are sterile, after which they are 
ready for use. 

The blood-serum medium produced by this older method is 
especially suited for the cultivation of certain pathogenic bacteria 
— for instance, the bacillus tuberculosis and the bacillus diphtherias 
— but we do not think that its superiority in this respect over the 
more readily prepared, firmly coagulated form above described is 
sufficiently marked to compensate for the great difficulties in its 
preparation. 

Litmus-milk is a form of culture-medium used for deter- 
mining certain of the physiological properties of bacteria. It 
consists of cow's milk which has been colored blue by litmus 
and containing a minimum amount of cream. A pint or so 
of strictly fresh milk is placed in a flask and steamed in the 
steam sterilizer for about half an hour. When it is removed 
it w T ill be found that most of the cream has collected at the 
surface, and it is then easy to draw off the milk from the 
deeper layers with a pipette into a separate flask. To the 
milk from which most of the cream has been thus removed 
is added sufficient of an aqueous solution of litmus (freshly 
filtered) to give it a pale-blue color. The colored milk is 
then run into test-tubes (5 cm. deep in each tube) and ster- 
ilized, as indicated on page 8y, after which it is ready for 
use. It is of great importance that the milk be fresh. If 
it is not, it may contain spore-bearing bacilli which it is 
practically impossible to kill by the steam sterilization. 

Potato -cultures according' to Bolton. — Potatoes — pref- 



BA CTERIOL O GICA L ME THODS. 



Pepton, 

Sodium chlorid, 
Distilled water, 



10 grams ; 

5 " 
iooo c.c. 



erably old ones — are first washed to remove all the coarser 
particles of soil, and then solid cylinders are cut out of them 
with a cork-borer or apple-corer. These cylinders should 
be of a suitable diameter to fit into the test- 
tubes used for other culture-media, and should 
be about 5 cm. long. They are then cut 
longitudinally in an oblique direction with a 
sharp knife, so that a smooth slanting sur- 
face is produced, beginning near one end 
and extending diagonally to the other end. 
The pieces of potato thus prepared are next 
to be washed in running water over night. 
After washing, each piece is placed in a test- 
tube, the larger end resting on the bottom 
of the tube, a few drops of water being added 
to prevent drying, and then sterilized as in- 
dicated on page 87. If desired, a small piece 
of glass rod may be placed in the bottom of 
the tube to elevate the potato above the few 
drops of water (Fig. 13). 

Dunhams Pepton Solution. — Formula 
for 1000 c.c. : 





FIG. 13.— Potato- 
culture. 



The pepton and sodium chlorid are dissolved 
by boiling and the mixture filtered. The clear filtrate is 
then run into test-tubes, each test-tube being filled to a 
depth of 5 cm., and is to be sterilized as indicated on page 
87, after which it is ready for use. 

The Adjustment of the Reaction of Culture -media 
by Titration. — Because comparatively small variations in 
the reaction of culture-media may have a marked effect upon 
the morphology and mode of growth of bacteria grown 
upon them, a more exact adjustment of their reaction than 
is possible with litmus paper is desirable. This is especially 



84 PATHOLOGICAL TECHNIQUE. 

important for media used for the cultivation of the bacteria 
of water, of soil, and of the air. For ordinary purposes of 
cultivation of bacteria, especially of the pathogenic forms, 
the adjustment of the reaction with litmus paper, as else- 
where described, if carefully done, will be found to be suf- 
ficient. 

The more exact method of adjusting a reaction is one of 
titration with phenolphthalein as an indicator. The method 
is as follows : When the culture-medium, whether it be 
bouillon, agar-agar, or gelatin, has been neutralized with the 
aid of litmus paper, made up to the proper volume, and 
when it is all ready for filtering, as described elsewhere, 5 c.c. 
of it are transferred by means of a pipette to a 6-inch por- 
celain evaporating dish ; to this 45 c.c. of distilled water are 
added, and the 50 c.c. of fluid are boiled for three minutes over 
a flame to expel any carbon dioxid which may be present. 

Next, 1 c.c. of a 0.5 per cent, solution of phenolphthalein in 
50 per cent, alcohol is added to the mixture in the dish, and 
immediately after this enough of a twentieth normal solution 
of sodium hydroxid is cautiously run into the dish, from a 
burette, to produce a pink color in the mixture. The judg- 
ment of the proper color which indicates that sufficient 
alkali has been run in requires some practice. The color to 
be obtained is a bright pink. The appearance of the proper 
pink color is preceded by a pinkish darkening of the fluid 
which may deceive the inexperienced. 

The quantity of the twentieth normal sodium hydroxid 
solution required to effect this result is then read off from 
the burette. The number of cubic centimeters required 
denotes the percentage by volume of a normal solution of 
sodium hydroxid which would be required to make the total 
volume of culture-medium neutral to phenolphthalein. That 
this is so will be apparent after a simple calculation. 

The reaction recommended by the Bacteriological Com- 
mittee of the American Public Health Association as a 
standard to which culture-media should be adjusted is such 
that 1.5 per cent, of a normal solution of sodium hydroxid 
would be required to be added to the medium to make it 



BACTERIOLOGICAL METHODS. 85 

neutral to phenolphthalein. This reaction corresponds 
closely to a faint alkalinity toward litmus, for the neutral 
point of phenolphthalein is not identical with that of litmus. 
The adjustment of the reaction to this standard is effected by 
adding to the bulk of the culture-medium sufficient normal 
sodium hydroxid solution or normal hydrochloric acid solu- 
tion. 

For example : If the titration shows that 5 c.c. of the 
medium requires 1.9 c.c. of the twentieth normal solution of 
sodium hydroxid to make it neutral to phenolphthalein, then 
the total mass of the medium will require the addition of 
1.9 per cent, or 19 c.c. for a liter, of a normal solution of 
sodium hydroxid to make it neutral ; but the reaction re- 
quired is such that 1.5 per cent, of a normal solution of 
sodium hydroxid should be required to make it neutral. 
Therefore, 0.4 per cent, or 4 c.c. for a liter, of a normal 
solution of sodium hydroxid should be added to the main 
mass of the medium. 

When the calculated amount of normal solution has been 
thoroughly mixed with the medium and the latter boiled for 
a few minutes, the titration should be repeated as above 
described. If the desired reaction is not found to be present, 
then further adjustment by addition of the calculated amount 
of normal acid or alkali solution should be made. It is not 
to be expected that the first addition to the medium of the 
calculated amount of normal solution will give exactly the 
required reaction in every case. This is due to unknown 
side reactions which take place in the culture-media. 

When the reaction has been sufficiently adjusted, the 
medium is to be filtered and is then ready to be distributed 
in test-tubes. 

The methods of making the normal and twentieth normal 
solutions required may be found in standard works on chem- 
istry. If one has not some knowledge of chemistry, he 
would better have the solutions made by a chemist. 

The filling of the test-tubes with the fluid culture- 
media described in this section is best effected by means of 
a funnel of a capacity of about a liter. In this the fluid me- 



86 PATHOLOGICAL TECHNIQUE. 

dium is placed, and by means of a pinch-cock the requisite 
quantity of medium is run into each test-tube. In running 
the medium into the test-tubes the left hand holds the test- 
tube while the right hand removes the cotton stopper and 
manipulates the pinch-cock (Fig. 14). Care should be exer- 
cised not to allow any of the medium to come in contact with 
the neck of the test-tube, for it will make the cotton stopper 




Hi i|. 



FIG. 14. — Method of filling test-tubes with culture-medium (Warren). 



stick to the walls of the tube. To avoid this, the delivery- 
tube of the apparatus should be inserted some distance into 
the test-tube in filling. 

The quantity of culture-medium run into each test-tube 
varies according to the form of culture desired and the cha- 
racter of the medium. In the case of liquid media and solid 
media designed to be used in the form of " stab " cultures the 



BACTERIOLOGICAL METHODS. 87 

tubes should be filled to a depth of 5 cm. For " slant " cul- 
tures of solid media a depth of about 3 cm. is sufficient, or 
enough to give a slanting surface from the bottom of the 
tube to about halfway up the opposite side. 

Small Ehrlenmeyer flasks are sometimes used for bouillon 
cultures. These are of about 100 c.c. capacity, and are filled 
to a depth of about I cm. with the medium. The necks are 
provided with cotton stoppers, and the whole sterilized and 
treated as test-tube cultures. 

STERILIZATION OF CULTURE=HEDIA. 

In general, the sterilization of culture-media is effected by 
allowing them to remain exposed to the action of live steam 
in the steam sterilizer for twenty to forty-five minutes on 
three successive days. The period of exposure to live steam 
varies somewhat with the kind of culture-medium. A single 
exposure for the time mentioned is sufficient to destroy all 
bacteria present in what is called the vegetative or non-re- 
sistant form, but it will not kill spores, which represent a 
stage in the life-history of certain bacteria, in which form the 
organism is highly resistant to sterilizing agents. 

Under favorable conditions, such as are to be found in 
culture-media at ordinary room-temperature, these spores 
develop into the vegetative or non-resistant form, which 
are easily destroyed by heat. Therefore, in order that 
the culture-medium be made sterile, it is necessary that it be 
again subjected to the action of steam on the following day 
for the same length of time, when the vegetative forms of 
the few surviving spores will have developed, and will be 
capable of destruction by ordinary exposure to live steam. 

As a further precaution a third similar sterilization on the 
next day is necessary. Therefore, three steam sterilizations, of 
from twenty minutes to one hour each, on successive days, are 
required to keep culture-media sterile for an indefinite period. 1 

1 As has been pointed out by Theobald Smith, this intermittent sterilization 
at ioo° C. may not be sufficient in some cases to kill all the spores, 
because the condition in the media may not be favorable for their development 
into vegetative forms, between sterilizations. This seems to be especially true 



88 PATHOLOGICAL TECHNIQUE. 

A freshly prepared culture-medium must be sterilized on 
the same day that it is prepared, or by the next day it may 
be found to contain living bacteria, especially if kept over 
night in a warm room. 

For the purpose of sterilization the test-tubes containing 
the media are to be placed in a round wire basket which fits 
into the steam sterilizer, 1 thus facilitating the handling of the 
tubes and also keeping them upright. 

If the medium be in a flask ready for running into test- 
tubes, and if it be not convenient to do this the same day, 
the medium may be preserved as long as desired by insert- 
ing a cotton stopper into the mouth of the flask and then 
sterilizing as above indicated. 

The time of each sterilization for bouillon, agar-agar, 
blood-serum, etc. may be fixed at half an hour ; for potato- 
culture tubes and for litmus-milk, forty-five minutes. 

In the case of gelatin, however, the time of exposure to 
live steam should be shorter, owing to the danger of destroy- 
ing the solidifying power of the medium by too much heat- 
ing. Twenty minutes' exposure is sufficient. 

Large quantities of culture-media contained in flasks 
should be sterilized for forty-five minutes to an hour, for 
obvious reasons. 

The sterilization of culture-media may also be effected in 
an autoclave. This is a steam-tight chamber for sterilizing 
by steam under pressure. Various forms of this apparatus 
are on the market. The great advantage of the use of this 
apparatus is that a single sterilization is sufficient. Exposure 
of culture-media in tubes, of glassware, and of other apparatus, 
in it to a temperature of uo° C. (6 lbs. pressure) for fifteen 
minutes suffices for sterilization in most cases. For the 

of certain anaerobic spore-producing bacilli. Such spores may be the source of 
contamination of the culture-medium when it is placed under anaerobic condi- 
tions, or when the medium is used for anaerobic cultures, because strictly ana- 
erobic bacteria may grow in company with other bacteria under aerobic con- 
ditions. Therefore, in those cases in which it is important to be certain of the 
lute sterility of the culture-medium, sterilization in the autoclave (q. v.) is 



necessary. 

x The " Arnold Steam Sterilizer" No. 5 is recommended. 



BACTERIOLOGICAL METHODS. 89 

sterilization of culture-media in bulk, about thirty minutes at 
this temperature is necessary. 

In using the autoclave it' is requisite that the confined air 
be replaced by superheated steam. To insure this, the time 
of sterilization should be reckoned only from the time when 
the theoretical temperature, as registered by the pressure- 
gauge, corresponds with that recorded by the thermometer. 1 

The Storage of Culture-media. — In order to prevent 
evaporation and the invasion of moulds, the cotton stopper 
should be cut off close to the mouth of the tube or flask, the 
surface of the stopper well singed with a flame, and the 
mouth of the tube or flask tightly closed with a cork. 

Immediately before insertion, the portion of the cork that 
enters the tube or neck of^the flask should be charred in a 
flame. If thought desirable, the cork may be sealed with 
paraffin. 

II. BACTERIOLOGICAL EXAMINATIONS. 

The bacteriological examination of material obtained from 
the individual during life or at autopsies should determine 
whether bacteria are present or not, and if present their 
species and comparative number. At autopsies the exam- 
ination should also determine the extent of the distribution 
of any infecting bacteria throughout the principal internal 
organs. 

This is accomplished chiefly by means of two methods of 
examination — viz., the direct examination with the microscope 
of cover-glass preparations, and the results of cultures made 
from the tissues. Both of these methods should be em- 
ployed together, but the culture method is perhaps the most 
important. A third but less frequent method is the inocula- 
tion of animals with pieces of tissue or material taken from 
the body. 

Methods of Collecting Material. — In the bacterio- 
logical examination of pathological material obtained from 
the individual during life, it is of obvious importance that the 

1 Bacteriological Committee Report, Jour. Atner. Pub. Health Assoc, Jan., 
1898. 



go 



PA THOL O GICA L TE CHNIQ UE. 



material be protected from the invasion of bacteria from 
without, and that in its collection every object with which it 
comes in contact be free from living bacteria. 

To fulfil these requirements the material may be con- 
veniently collected in any of the following ways : 

I. It may be obtained directly from the individual by 
means of the sterilized platinum wire, 
and cover-glass preparations, cultures, 
and, if necessary, animal inoculations, 
made at once. 

2. Since a very small quantity of the 
material usually suffices for the purposes 
of examination, it may often be very 
conveniently collected and brought to 
the laboratory on the so-called" swabs," 
where it can be subjected to the vari- 
ous manipulations at leisure. 

The " swab " consists of a piece of 
rather stiff wire about six inches long, 
on one end of which is firmly twisted 
a pledget of absorbent cotton, so that 
the end of the wire is well covered. 
This is placed, cotton end first, in a 
test-tube, which is then provided with 
a cotton stopper (Fig. 15), and the 
whole sterilized in a hot-air sterilizer 
by heating to 150 to 180 C. during 
about half an hour. A large number 
of " swabs " in test-tubes may be kept 
hand sterilized and ready for use. 
When it is desired to secure material 
in g pus and fluids for bac- f or bacteriological examination on a 

teriological examinations . ,, , . , 

(Warren) swab, the cotton stopper is removed, 

the swab taken out, and the cotton end 
brought in contact with the pus or exudate in such a manner 
that some adheres to the cotton. The swab is then imme- 
diately replaced in the test-tube, the cotton stopper returned 
to its place, and the whole then carried to the laboratory. 




Fig. 15. — Sterilized test- 
tube and swab for collect- 



on 



BACTERIOLOGICAL METHODS. 9 1 

111 these manipulations care should be taken to avoid 
touching with the swab anything but the material which it 
is desired to examine, otherwise the material may be con- 
taminated with other bacteria than those originally present 
in it. 

By means of swabs material for examination from pus or 
exudates may be secured and brought to the laboratory in 
most instances. They are especially useful in surgical work, 
in which it is often desirable to determine the character of 
the organism present in a pus-formation or exudation with- 
out waiting to summon a bacteriologist or to collect the 
necessary cover-glasses, culture-tubes, platinum needle, etc. 
The swabs and their test-tubes may be kept on hand in a 
sterile condition, so that they may be handled by the ope- 
rator or an assistant. 

3. Fluid material may be collected by aspiration or other- 
wise. In the case of fluids care should be taken that every- 
thing with which the fluid comes in contact be clean and 
sterilized by heat if possible. The use of antiseptics, 
such as carbolic acid or corrosive sublimate, is to be 
avoided. 

If a hypodermic syringe is used in obtaining material, it 
should be of a construction which will admit of sterilization 
by heat, and it should be so sterilized before using. 

In the collection of pathological fluids, especially peri- 
toneal exudates, a special form of apparatus has been found 
most useful. It consists essentially of a glass tube, about 
14 cm. long and about 7 mm. in external diameter, one end 
of which is narrowed to a small opening and rounded off, 
while to the other end is attached a small rubber bulb like 
that on a " medicine dropper." It is to be kept ready for 
use in a test-tube, stoppered with cotton (see Fig. 16), the 
whole having been sterilized as are surgical dressings. The 
rubber bulbs are not expensive. Any number of pieces of 
this apparatus may be kept on hand in sterile condition. 

When it is desired to obtain a sample of peritoneal or 
other fluid for bacteriological examination, the apparatus is 
removed from the test-tube and the fluid aspirated into it by 



9 2 



PA THOL O GICAL TE CHNIQ UE. 



manipulation of the rubber bulb. It is then replaced in the 
test-tube. The fluid thus obtained should be free from con- 
tamination and may be readily transported to the laboratory 
for examination. 

Cover-glass Preparations. — The method of demon- 
strating the presence of bacteria in pathological material by 
means of cover-glass preparations depends upon the fact 
that bacteria have the property of being 

f colored by certain of the aniline dyes, 

and thus may be more readily seen 
by the microscope. The cover-glasses 
are best kept in alcohol, and as re- 
quired for use wiped dry with a soft 
cotton cloth. A cover-glass prepara- 
tion is made as follows : A very small 
amount of tissue or material to be 
examined is thinly spread over the 
surface of a clean thin cover-glass 
with the platinum wire or " loop " 
described on page 96 so as to give a 
streaked appearance to the surface, but 
not a definite layer which is ordinarily 
too thick for satisfactory examination. 
The charged cover-glass is then dried 
by holding it in the fingers over the 
flame of a Bunsen burner, and when 
dry it is placed, charged surface 
uppermost, in the grasp of a pair of 
cover-glass forceps, 1 by means of 
which it is passed rapidly three times 
flame of a Bunsen burner or alcohol lamp. 
This " fixes " the material on the glass, and the prepara- 
tion is then ready for staining by one of the various 

In staining, the cover-glass is held 

upper- 




FiG. 16. — Apparatus for 
the collection of patholog- 
ical fluids. 



through 



the 
fixes " 



then 
methods given below, 

by means of the forceps with the charged side 
most and level, and the surface is then completely covered 



1 The form of cover-glass forceps known as Stewart's is recommended. 
They may be obtained from American dealers in bacteriological apparatus. 



BACTERIOLOGICAL METHODS. 93 

with the staining fluid, which is poured upon it from a drop- 
ping-bottle. 1 It may then be heated over the flame oi the 
Bunsen burner, washed in water, and submitted to any further 
manipulation which may be necessary while still in the grasp 
of the forceps. When the staining is completed the prepara- 
tion is next to be prepared for microscopic examination. 
This is done by placing the cover-glass, with as much water 
as will adhere to it, charged side downward, on a " slide," 
and then removing all remaining water, except a thin film of 
water between the slide and cover-glass, by gentle pressure 
with several thicknesses of filter-paper. The preparation is 
then ready for examination with an oil-immersion lens. The 
presence of this film of water is very essential for a satis- 
factory examination with the microscope, and its evaporation 
may be compensated for by a drop of water placed at the 
edge of the cover-glass. The preparation may also be 
mounted in balsam after carefully drying it first between 
filter-paper and then holding it in the fingers over the Bun- 
sen flame, but the examination in water mount is better, 
because the apparent size of the bacteria is greater in this 
than when mounted in balsam. 

It is of the greatest importance that cover-glass prepara- 
tions be made from all exudates or acute inflammatory con- 
ditions of organs or tissues, so that the results of cultures 
can be controlled and some idea formed of the number and 
character of the bacteria present. They are of especial use 
as enabling one sometimes to recognize the presence of an 
organism which does not grow in the culture for some 
reason, and whose presence might escape notice, while their 
importance in many cases in the identification of the pneu- 
mococcus and the bacillus tuberculosis must be apparent. 
In certain cases it is best to examine the material in its 
natural state and without drying and staining. This is espe- 
cially true of suspected infections with actinomyces and the 
amebae coli. In these cases the material should be spread 
over a cover-glass, and this placed, while the material is still 

1 The form of drop-bottle known by dealers in bacteriological supplies as the 
" T. K. patent," with flat stopper, is the best. 



94 PATHOLOGICAL TECHNIQUE. 

moist, charged surface downward, on a " slide," and then 
examined with various powers of the microscope. If neces- 
sary, a small amount of normal salt solution (0.6 per cent.) 
may be added to dilute the material and facilitate the ex- 
amination. 

Staining Methods for Cover-glass Preparations. 1 — 
Simple staining is used for the demonstration of bacteria in 
general, and also useful in gaining an idea of the character 
of the cellular elements in the preparation. 

Loffler's alkaline methylene-blue solution is perhaps the 
best staining fluid to use for simple staining, for it does not 
stain so diffusely and intensely as do the other commonly 
used dyes, such as fuchsin and gentian violet, which may 
also be employed. 

The cover-glass, covered with the staining fluid, should be 
warmed over the Bunsen flame, so that the fluid steams, for 
about fifteen seconds. Boiling should be avoided. The 
preparation is then washed in water for two or three seconds 
and mounted. 

Pappenheim's pyronin and methyl-green mixture may 
be used as above described in place of Loffler's methylene- 
blue solution. This mixture is composed of: 

Stained aqueous solution of methyl-green, 3-4 parts ; 
" " " pyronin, I-I J " 

Bacteria are stained brilliant red and the nuclei of cells are 
stained blue or purple. The mixture is said to keep several 
weeks. 

Gram's Method of Staining. — 1. Cover the preparation 
with aniline-gentian-violet solution for thirty seconds. 

2. Wash in water for two or three seconds. 

3. Cover the preparation with Gram's solution of iodin 
for thirty seconds. 

4. Wash with 95 per cent, alcohol until the color ceases 
to come out of the preparation. 

5. Wash in water for two or three seconds and mount. 
Certain bacteria are stained by this method, while others 

are not. Bacteria when stained by it appear dark blue or 

1 The formulae for staining fluids will be found in Part III. (see Index). 



BACTERIOLOGICAL METHODS. 



95 



black, while the nuclei of the cells are rather faintly stained 
or not stained at all. The method is especially useful in the 
demonstration of bacteria which are stained by it when 
they are present in small numbers or when a few Gram- 
staining bacteria are mixed among numbers of bacteria 
which do not stain by this method. It also has some value 
as a means of differentiating between bacteria which may be 
very much alike in size and shape. 

In the following table the behavior of the more important 
pathogenic bacteria toward the method of Gram is indicated : 



Stained by Gram's Method. 
Staphylococcus pyogenes aureus. 
Staphylococcus pyogenes albus. 
Streptococcus pyogenes. 
Streptococcus capsulatus. 
Pneumococcus. 
Micrococcus tetragenus. 
Bacillus diphtherise. 
Bacillus tuberculosis. 
Bacillus of anthrax. 
Bacillus of tetanus. 
Bacillus aerogenes capsulatus. 
Bacillus of malignant edema. 



Decolorized by Gram's Method. 
Gonococcus. 

Diplococcus intracellularis meningi- 
tidis. 
Typhoid bacillus. 
Bacillus coli communis. 
Spirillum of Asiatic cholera. 
Bacillus pyocyaneus. 
Bacillus of influenza. 
Bacillus of glanders. 
Bacillus proteus. 
Bacillus mucosns capsulatus. 
Bacillus of dysentery. 
Bacillus of bubonic plague. 
Bacillus of chancroid. 



Special staining" methods for cover-glass preparations 
will be found in the section on Special Bacteriology. 

Examination by Cultures. — The demonstration of the 
presence of bacteria in a tissue or exudate by means of cul- 
tures consists in bringing a small amount of the material to 
be examined in contact with some solid nutrient substance 
in which the bacteria will thrive. On this the bacteria by 
multiplication form masses or colonies visible to the naked 
eye, and present appearances which enable a practised eye 
in many cases to recognize the species of the bacteria of 
which they are composed. Of the solid culture-media de- 
scribed in the preceding section, the coagulated blood-scrum 
is distinctly the best to use for the demonstration of the 
presence of bacteria in routine pathological work, because 



96 PATHOLOGICAL TECHNIQUE. 

certain of the most important pathogenic bacteria grow bet- 
ter upon it than upon agar-agar or similar media. The other 
media have important uses in the study of the bacteria after 
their isolation from the tissues, and in certain instances spe- 
cial media are to be used, as will be pointed out in the fol- 
lowing pages. The blood-serum medium here described 
has been found entirely suitable for the isolation of the 
bacillus tuberculosis from tubercular lesions, which proves 
its efficiency as a culture-medium. 

Method of Preparing- Cultures on Blood-serum. — The 
preparation of cultures on the coagulated blood-serum con- 
sists in distributing over the surface of the medium in a test- 
tube as much of the tissue or other material as will adhere 
to the end of a piece of stiff platinum wire hammered flat 
at the end. The wire is fixed in the end of a glass or metal 
rod, and should be about 8 cm. long. It should have a 
rounded spatula-like extremity, and should be thick enough 
not to bend easily. In making cultures from clinical mate- 
rial, the platinum loop may be used for fluids. 

The " platinum wire" or "loop" consists of a piece 
of platinum wire of about 22 gauge, 2^ to 3 inches long, 
fixed in the end of a small glass or metal rod 8 or 10 inches 
long. It is often of great convenience to have two of these 
instruments, one with the wire curled into a simple loop 
about 1 to 2 mm. in diameter at the free end, and the other 
a straight wire with the free extremity hammered flat into 
a very small spatula. The latter is of great utility in pick- 
ing up minute portions of bacterial colonies. 

Both this instrument and the stiffer wire, above mentioned, 
should be heated to a red heat in a flame immediately before 
using, in order to destroy any bacteria that may be upon 
them. 

If the material is on a " swab," the surface of the blood- 
serum or other media may be conveniently inoculated directly 
by gently rubbing the swab over it. In this case it is usually 
best to make a dilution or two by means of the platinum wire, 
as described below, especially if there be a large amount 
of material on the swab or if the cover-glass examination 



BACTERIOLOGICAL METHODS. 97 

has shown that a large number of bacteria are present. In 
any case it is important that the infected material be spread 
over all of the surface of the medium, and not in the form 
of one or two narrow streaks. 

It is, of course, essential that the material brought in con- 
tact with the culture-medium should be free from bacteria 
not originally present in it, or that it be not contaminated 
with bacteria from outside sources. Therefore, in taking 
material from the interior of organs and tissues the surface 
is first sterilized by searing it with a hot knife, such as an ordi- 
nary case-knife, which has been heated in the Bunsen flame, 
and then, through a small incision made with another hot 
knife in this seared or sterilized area, the material from the 
interior is collected on the end of the platinum wire, which 
has also been previously heated in the Bunsen flame to 
sterilize it, and then cooled either by plunging it in the 
water of condensation of the culture-tube for a few seconds 
or by moving it about in the interior of the tissue. 

In the case of exudations on free surfaces, however, this 
searing is impossible, and therefore care should be exercised 
at the autopsy not to contaminate any such exudate by 
handling before the material for culture has been obtained 
with the platinum wire. The material thus secured is then 
transferred by means of the platinum wire to the surface of 
a blood-serum culture-tube, and the infected wire gently 
rubbed over all of the surface of the culture-medium, avoid- 
ing, however, the breaking of the surface. // is important 
that the material be well distributed over the nutrient surface. 
If the material is suspected of containing a large number of 
bacteria, as in the case of suppurations or acute inflamma- 
tory lesions, a second tube should be inoculated from the 
first one by touching the platinum wire, previously sterilized 
and cooled, to the infected surface of the first tube, and then 
gently rubbing the infected wire over the surface of the 
second tube. This operation is called " diluting." The 
object of this is to obtain, after the development of the cul- 
ture, a sufficiently small number of colonies in the second 
tube, so that they may be discrete — /. e\ separated from one 



98 PATHOLOGICAL TECHNIQUE. 

another — and thus be enabled to exhibit their characteristic 
appearances, which are largely lost when the colonies are so 
numerous as to be confluent. 

If thought desirable, a third tube may be similarly inocu- 
lated from the second, but this is rarely necessary. In mak- 
ing these " dilutions " it is well to cool the platinum wire in 
the water of condensation of the sterile tube before touch- 
ing it to the infected surface of the other tube. As a rule, 
one tube will be sufficient to obtain discrete colonies from 
organs or tissues in which no suppurative or exudative con- 
dition is present. 

Anaerobic cultures are indicated in certain cases. For 
anaerobic methods, see pp. 121, 122. 

After the manner above indicated cultures are to be made 
at the autopsy as a matter of routine from the blood of the 
heart, from the liver, the spleen, the lung, and the kidney. 
Cultures are also to be made from any acute inflammatory 
lesion in any situation. 

As each culture-tube is infected it is to be labelled with 
the name of the organ or of the material from which it was 
infected, and with the date. For this purpose small paper 
labels coated with mucilage are used. 

The culture from the blood of the heart should be made 
before the removal of that organ from the body, by searing 
the right ventricle and then puncturing it with a sterilized 
knife to admit the platinum wire. The amount of blood 
used for the culture should be as much as will adhere to the 
platinum wire. Cultures from vegetations in acute endo- 
carditis are not usually of much value unless they are suf- 
ficiently large to enable a sterilization of their surface to be 
effected and material for culture secured from their interior. 

Cultures from the Blood during I4fe.— This pro- 
cedure is coming more and more into use for diagnostic 
purposes in cases of suspected bacterial infection of the 
circulating blood. The blood is obtained from one of the 
large veins at the flexure of the elbow by means of an anti- 
toxin or similar syringe, and in most cases is immediately 
mixed with an excess of sterile bouillon. About 10 c.c. or 



BACTERIOLOGICAL METHODS. 99 

more of blood should be taken. A convenient way is to 
distribute the blood directly by means of the syringe in 
quantities of 1 or 2 c.c. among flasks, each containing 200 
to 400 c.c. of sterile bouillon. The blood is thus highly 
diluted in order to obviate its bactericidal action. 

In the case of general infection with anaerobic bacteria 
the blood should be mixed immediatelv with melted ag-ar- 
agar at 40 C. in test-tubes, in the proportion of one part to 
two or three parts of agar-agar. The mixture should fill the 
culture-tubes to a height of about 8 cm. For the method 
of cultivating gonococci from the blood see page 146. 

The strictest aseptic precautions must be observed in ob- 
taining the blood and in mixing it with the culture-medium. 

Intraperitoneal inoculation of mice may also be made with 
\ to 1 c.c. of the blood. This may give rise to strepto- 
coccus or pneumococcus septicemia. 

The Inoculation of Animals. — The inoculation of 
animals directly with pathological material is often of im- 
portant diagnostic value. In routine pathological work it 
is mainly useful in determining the presence of the pneumo- 
coccus or of the bacillus tuberculosis when the ordinary 
methods are considered inadequate. 

The methods of inoculating animals are described on 
pp. 1 1 6- 1 2 1 . 



III. THE METHODS OF STUDYING BACTERIA IN 
CULTURES. 

The cultures made as described in the last section, having 
been in the incubator for eighteen to twenty-four hours, 
are next to be studied, and the identity or diagnosis of the 
bacteria whose colonies have grown out upon them is 
to be established. The identification of the infecting bac- 
teria present in most cases may be made from a con- 
sideration of the size, color, and general appearance of the 
colonies as they appear on the surface of the blood-serum 
when taken in connection with the morphology of the bac- 
teria composing them. In some cases, however, this may 

1 C f 



IOO PATHOLOGICAL TECHNIQUE. 

not be sufficient evidence upon which to base the diagnosis, 
and it may be necessary to obtain further facts in regard to 
a given organism in order to identify it with a sufficient 
degree of certainty. Thus it may be necessary to observe 
the appearances of its growth in pure culture in various 
media, and to ascertain whether it produces certain chemi- 
cal changes in the media by its growth. Its ability to grow 
with or without oxygen, its reaction toward staining agents, 
whether it has independent motion or not, and its effects 
upon animals by inoculation, are also points which may 
have to be determined to enable one to make a positive diag- 
nosis of the species to which the organism belongs. There- 
fore, in the study of the colonies of the bacteria which 
have developed in the cultures a familiarity with certain 
fundamental bacteriological methods is necessary. These 
will be described in this section. 

i. COVER=GLASS PREPARATIONS FROM CULTURES. 

A minute proportion of a colony or bacterial growth, the 
component organisms of which are to be examined, is picked 
up on the end of the platinum wire, which has been pre- 
viously heated in the Bunsen flame and cooled, and is thinly 
distributed on the surface of a cover-glass by gentle move- 
ments of the platinum wire. It is very important that the 
bacteria should be more or less separated from one another 
in places, so that a good view of the individual organisms 
may be obtained. This can often best be effected by placing 
a minute drop of water on the cover-glass first, and then 
moving the infected end of the platinum wire back and forth 
through this. The preparation is then dried between the 
fingers over the Bunsen flame, and next, having been 
grasped with the Cornet forceps, is to be rapidly passed three 
times through the Bunsen flame. While still held by the 
forceps, it is then stained by covering it from a dropping- 
bottle with the staining solution, and washed in water or 
submitted to any other manipulation which may be required. 

The staining solutions ordinarily employed are carbolic- 
fuchsin, aniline-gentian-violet, and Loffler's alkaline methy- 



BACTERIOLOGICAL METHODS. 10 1 

lene-blue. If methylene-blue be used, it is best to steam 
the preparation in staining for about ten seconds, but in the 
case of the other stains this is not necessary, for they stain 
deeply almost immediately, so that the staining solution 
need not remain longer in contact with the bacteria than a 
few seconds. After staining, the cover-glass is to be washed 
in water and mounted for examination, as described on page 
92 in the case of cover-glass preparations from tissues. 

Gram' 's method of staining may also be used for cover-glass 
preparations from cultures. As has been pointed out elsewhere 
(see page 94), this method does not stain all species of bacteria, 
but some species are stained by it and others are not. This fact 
is sometimes useful in aiding in the identification of a given 
organism, and as enabling one to recognize the presence of a few 
Gram-staining bacteria among a large number of others which are 
unstained. 

In this connection it should be pointed out that bacteria which 
are stained by this method, when taken from cultures a few days 
old, may not be stained by it if taken from older cultures. There- 
fore, Gram's method, if used as a means of differentiation, should 
be applied only to bacteria in actively growing cultures. 

Bacteria stained by this method have a blue-black color. 

For a list of bacteria that stain by Gram's method see page 95. 

The Staining- of Spores. — Spores take up the anilin dyes 
with difficulty, probably owing to their dense protective envelope. 
When once stained, however, they do not give up their color 
easily, and resist decolorizing agents. The cover-glass prepara- 
tions should be thinly spread. 

Abbott' 's Method. — 1. Stain the cover-glass preparation deeply 
with methylene-blue, heating repeatedly until the staining solu- 
tion boils, but do not boil continuously, during about one minute. 

2. Wash in water. 

3. Wash in 95 per cent, alcohol containing 0.2 to 0.3 per cent, 
hydrochloric acid. 

4. Wash in water. 

5. Stain for eight to ten seconds in aniline-fuchsin solution. 

6. Wash in water and mount. 

The spores are stained blue and the bodies of the bacteria red. 
Moeller'' s Method. — 1. Wash the cover-glass preparation in 
chloroform for two minutes. 

2. Wash in water. 

3. Treat with 5 per cent, solution of chromic acid one-half to 
two minutes. 

4. Wash in water. 

5. Stain with carbol-fuchsin, heating slowly until the fluid boils. 

6. Decolorize well in a 5 per cent, solution of sulphuric acid. 



102 PATHOLOGICAL TECHNIQUE. 

7. Wash in water. 

8. Stain in aqueous solution of methylene-blue (1 gram to 100 
c.c.) thirty seconds. The spores will be red, the bodies of the 
bacteria blue. 

The preliminary treatment with chloroform is to cleanse the 
preparation. 

Fiocca suggests the following rapid method: " About 20 c.c. 
of a 10 per cent, solution of ammonia are poured into a watch- 
glass, and ten to twenty drops of a saturated aqueous solution of 
gentian-violet, fuchsin, methylene-blue, or safranin added. The 
solution is warmed until vapor begins to rise, then is ready for 
use. A very thinly-spread cover-glass, carefully dried and fixed, 
is immersed for three to five minutes (sometimes ten to twenty 
minutes), washed in water, washed momentarily in a 20 per cent, 
solution of nitric or sulphuric acid, washed again in water, then 
counterstained with a watery solution of vesuvin, chrysoidin, 
methylene-blue, malachite-green, or safranin, according to the 
color of the preceding stain. This whole process is said to take 
only from eight to ten minutes, and to give remarkably clear and 
beautiful pictures." 

The Staining of Flagella. — All motile bacteria are 
provided with delicate wavy, hair-like prolongations of their 
protoplasm, called flagella, which are of comparatively great 
length. These flagella are the locomotor organs of the 
organism. The number of them attached to each individual 
varies to a considerable extent with the species of the bac- 
teria. Thus the individuals of some species have but one 
flagellum, while the individuals of other species may have 
few or many springing from all parts of the organism. 

The flagella are not rendered visible by the ordinary 
methods of staining, but special methods are necessary for 
their demonstration. These methods depend essentially upon 
the use of a mordant, which causes the flagella to take up 
the stain. 

The cover-glasses must be absolutely free from grease in 
these methods, so that the -watery fluids may be spread 
evenly over them and not run into patches. The cover- 
glasses may be prepared by warming them in concentrated 
sulphuric acid for a time, washing them in water, and keep- 
ing them in a mixture of equal parts of alcohol and strong 
ammonium hydroxid solution. 

When used they are to be dried on a cloth which has pre- 



BACTERIOLOGICAL METHODS. IO3 

viously been soaked in ether and allowed to dry, in order 
that it may contain no trace of fat. Another way to treat 
the cover-glasses is to take them from alcohol, dry them 
with a clean cloth, and then heat them by means of the 
cover-glass forceps in the Bunsen flame to burn off any fat 
or grease. 

The bacteria must be distributed upon the cover-glass well 
separated from one another in these methods. They should 
not be subjected to too much manipulation in doing this, for 
the flagella are readily broken off. A good way is to make 
a dilute suspension of the bacteria in distilled water, and 
place one or two loopfuls of this on the cover-glass, not 
spreading with the loop, but making the suspension flow 
over the surface by inclining the cover-glass. 

Another way is to place two drops of water on a cover- 
glass — to draw the infected wire once through one of them 
across the surface, and then once through the other drop, 
thus making two streaks. This subjects the bacteria to less 
manipulation and gives a good distribution in places. 

The cover-glasses prepared as above indicated are to be 
allowed to dry in the air, and are then to be heated for a 
few seconds over a flame while held between the fingers. 
They are then ready to be stained by any of the methods 
given below. The cultures used for the preparations should 
not be older than eighteen to twenty-four hours. Solid 
culture-media, such as agar-agar, should be employed. 

Loffler's Method. — Treat the preparation for about one 
minute with the freshly filtered mordant solution, which is — 

Aqueous solution of tannic acid (20 grams tannic acid 

to 100 c.c. water), 10 c.c. ; 

Cold saturated solution of ferrous sulphate, 5 c.c. ; 

Saturated aqueous or alcoholic solution of gentian- 
violet or fuchsin, 1 c.c. 

The cover-glass is to be covered with this while held with 
the cover-glass forceps, as in ordinary methods of staining. 
The mordant, thus placed on the cover-glass, may be gently 
heated by holding the preparation high over the flame for a 



104 PATHOLOGICAL TECHNIQUE. 

period of about one minute, but it must not be boiled. After 
this the preparation is to be washed in water, and then 
stained with a freshly prepared and filtered solution of ani- 
line-gentian-violet or aniline-fuchsin, with gentle heating for 
thirty to sixty seconds. It is then again washed in water, 
and mounted in water or balsam for examination. 

In using this method, as well as others, an important thing 
to avoid is overheating. The mordant may be freshly mixed 
every time or kept indefinitely for use. 

The ferrous sulphate solution should always be freshly 
prepared, for it rapidly decomposes. The solution of tannic 
acid keeps well, however. 

The addition of varying quantities of acids or alkalies for 
different species of bacteria, as recommended by Loffler, is 
not necessary. 

Pitfield's Method as Modified by J. Blackburn Smith. — 

The mordant is prepared as follows : 

A saturated solution of mercuric chlorid, made by boiling, is 
poured while still hot into a bottle in which crystals of ammonia 
alum have been placed in quantity more than sufficient to saturate 
the fluid. The bottle is then well shaken and allowed to cool. 
To 10 c.c. of this fluid 10 c.c. of a freshly made 10 per cent. 
solution of tannic acid are added and 5 c.c. of carbol fuchsin 
solution. After mixing, filter. This mordant will keep. 

In staining, the mordant is filtered on to the cover-glass prepara- 
tion, which is heated until steam is given off during about three 
minutes. Boiling is to be avoided. The preparation is then 
washed in distilled water and is stained in a mixture of 1 c.c. of 
a saturated alcoholic solution of gentian violet and 10 c.c. of a 
saturated solution of ammonia alum. This mixture is filtered on 
to the preparation. 

BowhiU's Method. — Stain the preparation in the follow- 
ing solution for ten to fifteen minutes, slightly warming : 

Saturated alcoholic solution of orcein, 15 c.c. 

Aqueous solution of tannin, 20 : 80, 10 c.c. 

Distilled water, 30 c.c. 

This mixture is to be filtered before using. The saturated 
alcoholic solution of orcein should be at least ten days 
old. 



BACTERIOLOGICAL METHODS. 105 

G. H. Neuman's Method. — Make this mixture: 

Tannic acid, I gram ; 

Potassium alum, 1 " 

Distilled water, 40 c.c. 

Add to this, after the ingredients are dissolved, 0.5 gram 
of night blue, dissolved in 20 c.c. of absolute alcohol, mixing 
thoroughly. Filter off the precipitate that forms. The 
filtrate is the staining fluid. It will keep only a few days 
and should be filtered immediately before use. 

1. Stain the preparation (which has been dried at room- 
temperature) for two minutes or more, changing the fluid 
two or three times. 

2. Wash thoroughly in water. 

3. Stain with a saturated aqueous solution of gentian- 
violet for two minutes, in order to stain the bodies of the 
bacteria. 

4. Wash in water and mount. 

Williams' Method. — This is a modification of van Er- 
mengem's method along the lines of the modification of 
Hinterberger and others. It has been adopted by Dr. 
Hugh Williams after a large experience with various 
methods in the Laboratory of the Massachusetts General 
Hospital. 

The method is capable of giving black bacteria and fla- 
gella, with little or no precipitate. The method is as fol- 
lows : 

1. Cover the cover-glass with a mordant consisting of 

Alumnoi, 1 1 per cent, solution, 5 c.c: 

Osmic acid, 2 per cent, solution, 5 c.c. ; 

Tannin, 20 per cent, solution, 1 5 c.c. 

Shake the mixture, and add three drops of glacial acetic 
acid, and again shake. 

2. Apply the mordant less than one minute without heat- 
ing. Wash thoroughly in water. 

3. Cover the preparation, during about one minute, with a 1 

1 Farbwerke vorm. Meister Lucius u. Briining, Hochst a. M., Germany. 



106 PATHOLOGICAL TECHNIQUE. 

per cent, solution of silver nitrate to which sufficient ammonium 
hydroxid has been added to keep the silver in solution. 

4. Wash in water. 

5. Wash with 0.6 per cent, solution of sodium chlorid. 

6. Flood the preparation with a 30 per cent, solution of 
ammonium hydroxid, and immediately wash in water. 

7. Apply a few drops of Ortol photographic developer. 
The directions for making up this developer come with the 
Ortol. 

8. Wash in water. 

9. Cover with a 1 per cent, solution of gold chlorid 
during a few seconds. 

10. Wash in water, and apply Ortol developer for a few 
seconds. 

1 1. Wash in water, and cover with a 1 per cent, solution 
of mercuric chlorid for a few seconds. 

12. Wash in water. 

13. Apply Ortol developer for a few seconds. 

14. Wash in water, and repeat the application of chlorid 
of gold, the washing, and the application of the developer 
two or more times. Between the various applications of 
the chlorid of gold the preparation should be inspected 
with a high, dry lens to determine the progress of the stain- 
ing. This is readily done by placing the cover-glass, charged 
side upward, on a slide. In this way the process of impreg- 
nation with gold may be controlled ; for the flagella, if 
stained, may be easily seen with the high-power diy lens. 

The preparation is very conveniently held during the 
process in cover-glass forceps. The washing is best done in 
a small stream of water from a faucet. The various solutions 
are conveniently applied from dropping-bottles, see p. 93. 

It will be seen that the process consists essentially in 
the impregnation of the flagella with silver, followed by 
intensification, in the photographic sense, with mercury and 
gold. The object of the application of the sodium chlorid 
and ammonia is to remove the excess of silver compounds 
which adhere to the surface of the cover-glass in spite of 
washing. This excess of silver compounds is chiefly respon- 



BACTERIOLOGICAL METHODS. 107 

sible for the precipitates which appear on the preparation 
after the intensification. In spite of the application of the 
sodium chlorid and ammonia solutions, some precipitate 
will occur if the intensification is pushed too far. On this 
account it is advisable to observe the progress of the inten- 
sification under the microscope as above indicated. 

Although this method may appear complicated, in practice 
it requires but a few minutes to stain a preparation. 

2. METHODS OF OBTAINING PURE CULTURES. 

When it is desired to obtain a pure culture of bacteria, a 
colony or a portion of a colony of the organism is secured 
on the end of the sterile platinum wire, and transferred by 
this means to the culture-medium in another test-tube. The 
bacteria thus sown in the fresh culture-medium multiply 
there, and produce a growth visible to the naked eye which 
exhibits appearances more or less characteristic of the 
species. This growth, if the medium be a solid one, will 
usually be in the form of confluent colonies ; \i the medium 
be a fluid one, the growth may appear as a sediment with or 
without clouding of the liquid, or it may manifest other 
peculiarities according to the species to which the organism 
belongs. If other bacteria are present in the culture from 
which it is desired to obtain material for a pure culture, it is 
important that the material should be taken from a colony 
of the organisms which is well separated from other colonies 
— i. e. that the colony should be a so-called " discrete " one. 

In transplanting, the culture-tube containing the colony 
and the culture-tube that is to be infected from it are held 
side by side in the left hand in a slanting position in such a 
way as to give a good view to the operator of the surface of 
the media in each, while the cotton stoppers are removed 
and held between the fingers of the same hand (Fig. 17). 
The object of holding the tubes in a slanting position is to 
offer less chance of contamination from bacteria gaining en- 
trance to the culture-medium from the air. 

The platinum wire, which is manipulated by the right 
hand, is first sterilized by holding in the Bunsen flame until 



108 PATHOLOGICAL TECHNIQUE. 

it glows, and then cooled by contact with the media to be 
infected, after which its free end is carefully brought in 
contact with the discrete colony or pure culture-growth, 
and immediately inserted into the sterile tube to inoculate 
it. The manner of inoculating the sterile culture-medium 
in the other tube with the infected platinum wire will vary 
with the form and character of the culture desired. 

If the medium to be inoculated is a fluid one, the wire is 
simply immersed in it and moved back and forth once or 
twice. If the medium be a solid one in the form of a slant, 
the infected end of the wire is drawn over the surface once 




FIG. 17. — Method of holding tubes during inoculation. 

or twice from the bottom of the slant to its upper end ; or 
if the solid medium in the tube be arranged for a stab cul- 
ture (see page Jj), the infected wire is to be plunged once 
through the center of the mass to the bottom of the tube. 
After the tubes have been inoculated as above indicated, the 
wire is to be immediately withdrawn and the cotton stoppers 
replaced. They are then to be placed in the incubator for 
development. Gelatin cultures, however, must not be so 
treated, but are to be kept at room-temperature, for the heat 
of the incubator would cause the gelatin to become fluid. 

These details as to the manner of manipulating the cul- 
ture-tubes, cotton stoppers, and platinum wire also apply to 
the procedure described below. 



BACTERIOLOGICAL METHODS. IO9 

Method of Isolation of a Bacterium in Pure Cul- 
ture from a Mixed Growth. — If there is a more or less 
confluent growth of colonies of various kinds in a culture- 
tube, and it is desired to isolate a pure culture of one of the 
species of bacteria present, it is obvious that the first step is 
to obtain separate or " discrete " colonies of that organism. 
This is accomplished by securing a minute quantity of the 
growth on the end of the sterilized platinum wire (preferably 
from a spot where the organism is prevalent), and distrib- 
uting this over the surface of a sterile blood-serum tube by 
gently rubbing the end of the infected wire as thoroughly 




Fig. 18. — Diluting cultures. 

as possible over it. The wire is then sterilized in the Bunsen 
flame, cooled in the water of condensation of a second sterile 
blood-serum tube, next touched to the infected surface of the 
first tube, and the wire thus infected gently and thoroughly 
rubbed over the surface of the second. In a similar manner a 
third tube is then infected from the second, and then all the 
tubes placed in the incubator for eighteen to twenty-four hours. 
It is evident that comparatively few bacteria will be sown on 
the medium of the second tube, and still fewer on that of the 
third, so that the number of colonies which develop in the 
second tube will be less numerous than in the first tube, 
and those in the third tube still smaller in number. There- 
fore, in either the second or the third tube, or in both, the 
bacteria sown may be sufficiently few for discrete colonies to 
develop from them, and among these there ma}* be some 
composed of the bacterium which it is desired to isolate. 
From one of such discrete colonies pure cultures may then 



IIO PATHOLOGICAL TECHNIQUE. 

be prepared as described above. The second and third 
tubes used in this method are called " dilutions." The 
details of the manner of manipulating the tubes, etc. in this 
method may be understood from the description given on 
page 107 and from Fig. 18. 

The Plate Method of Petri. — Another method for obtaining 
discrete colonies of an organism from a mixed growth of 




Fig. 19. — Petri dish with colonies. 

several species is that known as the plate method of Petri. 
This is a modification of the original complicated method 
of Koch. 

The method consists in making " dilutions " in melted 
agar-agar or gelatin tubes, and then pouring the infected 
medium into shallow glass dishes (Fig. 19) previously steril- 
ized, in which it is allowed to solidify. A few bacteria are 
thus distributed throughout a thin layer of culture-medium 
in the " dilutions," and the colonies which develop from them 
are then more or less separated from one another, so that 
pure cultures may be obtained from them. In carrying out 
this method the procedure is as follows : 

Three sterile gelatin or agar-agar tubes are melted by heat 
and placed in a water-bath warmed to between 40 and 42 ° 
C. for several minutes, to bring the culture-medium to this 
temperature. This temperature is important especially in the 
case of agar-agar, for it is just above the solidifying point of 
that medium (3 8° C.) and yet not injurious to the vitality of 



BA C TERIOL O GICAL ME THODS. I I I 

the bacteria. The tubes are then infected successively from 
the bacterial growth or from the pathological material from 
which it is desired to obtain discrete colonies, in the same 
manner as described for the method with blood-serum tubes 
— viz. one tube being inoculated from the growth or tissue, 
a second tube or dilution from the first tube, and a third tube 
or dilution from the second tube, the platinum wire being 
sterilized after each inoculation. For making the " dilu- 
tions " a platinum wire bent into the form of a small loop 
(see page 96) is to be used, and as much of the culture-fluid 
as will adhere to it used for inoculating. The wire should 
be moved back and forth several times in the medium of each 
tube when inoculating it, in order to ensure a good distribu- 
tion of the bacteria throughout the fluid. The contents of 
each tube thus inoculated are then poured into sterilized Petri 
dishes, in which the culture-medium solidifies in a thin layer. 

The Petri dishes (Fig. 19) are of clear glass, circular in 
form, 10 cm. in diameter and about 1 cm. deep. Each is 
provided with a loosely fitting flat cover of glass. These 
dishes with their covers are to be sterilized before using by 
placing them in the steam sterilizer for half an hour or by 
heating them to 150 C. in the hot-air sterilizer. When cool 
they are ready to receive the contents of the inoculated test- 
tubes. In pouring, the cover of the dish is not to be re- 
moved any more than is necessary, and it is to be immedi- 
ately replaced, so that contamination from the air may be 
better avoided. It is very desirable that there be no dust 
about the place where the dishes are " poured," and no cur- 
rents of air. 

If agar-agar is used, the dishes thus prepared are to be 
put in the incubator for eighteen to twenty-four hours as 
soon as the medium is solid, which it becomes in a few min- 
utes ; but if gelatin be used, the dishes are to be set aside in 
a cool place, free from dust, to solidify, and are then to be 
kept at room-temperature for several days. Colonies first 
begin to appear in the gelatin usually after forty-eight hours. 

The method of Petri is of great utility in the study of bac- 
teria from the botanical standpoint, for it is especially adapted 



112 



PA TIIOL O GICAL TE C UNIQUE. 



for the study of the appearances of colonies under the low 
power of the microscope. It is, however, inferior to the 
method with blood-serum tubes for routine pathological 
work, for the following reasons : First : Certain pathogenic 
bacteria grow only feebly on the culture-media which it is 
necessary to employ in this method, while they grow com- 
paratively vigorously on blood-serum. Second: The method 
is complicated and much more troublesome and time-con- 
suming than the simple method described above. 

Bsmarch's Method of Roll-cultures. — A third method for ob- 
taining discrete colonies is that of Esmarch as modified by Stern- 
berg. It consists in melting and inoculating three gelatin or agar- 
agar tubes as described for the plate method of Petri, and then 




FIG. 20. — Esmarch tube on block of ice (redrawn after Abbott). 

distributing and solidifying the infected culture-medium over the 
inner surfaces of the tubes in the form of a thin layer by rolling the 
tubes on a block of ice while the medium in them is still fluid 
(Fig. 20). As in the plate method of Petri, the end in view is 
the distribution of a few bacteria throughout a thin layer, and the 
consequent development from them of discrete colonies. 

The tubes used for this purpose should contain sufficient cul- 
ture-medium to fill them to a depth of about 2 cm., but not much 
more than this, for with a greater quantity the preparation of a 
thin layer is difficult. 

In carrying out this method it is best to first make a depression 
in a block of ice with a test-tube filled with hot water. In this 
depression the culture-tube containing the fluid is placed in a 
nearly horizontal position, and rotated rapidly with the fingers 
until the medium is properly distributed and solid, care being 



BA CTERIOL O GICA L ME THODS. 



13 



exercised not to permit the medium to come in contact with the 
cotton stopper. The even distribution of the medium over the 
inner surface of the tube is best obtained by manipulating the tube 
while the medium is still fluid, in such a way as to moisten its 
inner surface up to about 1 cm. of the cotton stopper before pro- 
ceeding to rotate it on the ice. 

Gelatin is the best culture-medium to use in this method. Agar- 
agar can be used, but has the great disadvantage of readily slip- 
ping down toward the bottom of the tube if the tube is placed 
upright. It is necessary, therefore, to keep the tubes on their 
sides. The method has little or no advantage over the method 
of Petri. 

The Determination of the Motility of Bacteria. — 

This is done by observing the individual organisms, un- 




FlG. 21. — The " hanging drop " seen from above and in profile. 

stained, in a drop of bouillon or similar fluid under the oil- 
immersion lens. For this purpose a so-called " hanging drop" 
is prepared, for which a special form of slide known as a 
"hollow slide" is necessary. The hollow slide is a slide 
having a shallow circular concavity, about 1 cm. in diam- 
eter, ground out in its center (Fig. 21). 

In preparing- a hanging" drop the procedure is as follows : 
A small drop of a bouillon culture or of the water of con- 
densation of a blood-serum or agar-agar slant is placed in 
the center of a cover-glass by means of the platinum wire. 
The cover-glass is then placed, drop downward, over the 
circular depression in the hollow slide. To hold the cover- 
glass in its place and to prevent evaporation of the fluid in 
which the organisms are suspended, a little vaselin is painted 
around the margin of the depression before placing the 
cover-glass in position. The hanging drop thus prepared is 



114 PATHOLOGICAL TECHNIQUE. 

then examined by focusing upon it with the oil-immersion 
lens, a small aperture of the iris diaphragm of the conden- 
ser being used to render the bacteria visible by refraction. 
To facilitate focusing, the edge of the drop should be 
brought into the center of the field of the low-power ob- 
jective, and then the oil-immersion put in place and focused 
upon it, the edge of the drop being more readily seen as a 
sharp line, owing to refraction, than the organisms. Great 
care is necessary to avoid breaking the cover-glass in the 
effort to bring the bacteria into view. Hanging drops may 
also be prepared from suspensions of bacteria grown on solid 
media, by mixing a portion of the growth with a small quan- 
tity of bouillon. 

In the study of spore- formation the hanging drop is of great 
utility. Here the slide and cover-glass must be carefully steril- 
ized before using, the cavity between the cover-glass and the slide 
well sealed with vaselin, and other precautions taken to prevent 
contamination of the drop with other bacteria. The preparations 
may be placed in the incubator or on a ''warm stage " and the 
process of spore-formation followed. 

H. W. Hill's "Hanging-block" Method for the Observa- 
tion of Developing- Bacteria. — "Pour melted nutrient agar 
into a Petri dish to the depth of about one-eighth to one- quarter 
inch. Cool this agar and cut from it a block about one-quarter 
inch to one-third inch square, and of the thickness of the agar 
layer in the dish. This block has a smooth upper and under sur- 
face. Place it, under surface down, on a slide, and protect it 
from dust. Prepare an emulsion in sterile water of the organism 
to be examined if it has been grown on a solid medium or use a 
broth culture ; spread the emulsion or broth upon the upper sur- 
face of the block as if making an ordinary cover- slip preparation. 
Place the slide and block in a 37 C. incubator for five or ten 
minutes to dry slightly. Then lay a clean sterile cover-slip on 
the inoculated surface of the block in close contact with it, usu- 
ally avoiding air-bubbles. Remove the slide from the lower sur- 
face of the block, and invert the cover-slip so that the agar block 
is uppermost. With a platinum loop run a drop or two of naelted 
agar along each side of the agar block, to fill the angles between the 
sides of the block and the cover-slip. This seal hardens at once, 
preventing slipping of the block. Place the preparation in the in- 
cubator again for five or ten minutes to dry the agar seal. Invert 
this preparation over a moist chamber and seal the cover-slip in 
place with white wax or paraffin. Vaselin softens too readily at 37 
C, allowing shifting of the cover-slip. The preparation may then 
be examined at leisure. For bacillus diphtherias and organisms 



BACTERIOLOGICAL METHODS. 115 

of similar size, Zeiss ocular 5, objective y 1 ^, oil immersion, and a 
Welsbach light prove satisfactory, although a lower ocular and 
higher objective are better. The Abbe condenser is not used. If 
preferred, the Welsbach light may be concentrated by a four-inch 
lens, focal length seven inches. An incandescent electric lamp 
is very difficult to focus and does not yield good results." . . . 

"Bacteria multiplying readily at room- temperature can be ob- 
served in such a preparation exactly as an ordinary hanging drop 
is observed, except that the slide should be secured rigidly in 
some way to the microscopic stage to prevent shifting. For 
bacteria growing best at 37 C. a warm stage is required." * 

Celloidin Sacs. — By reason of the osmotic property of the 
celloidin these sacs permit the study both of the action of 
the body-fluids of an animal on bacteria contained in them 
and of the action of the metabolic products of the bacteria 
on the animal, without permitting the bacteria to invade the 
tissues. 

The method of Harris 2 for preparing these sacs seems to 
be an improvement on the method of McCrae, and is as 
follows : 

Affix a piece of glass tubing, 4 cm. long and 3 mm. in 
inside diameter, by heating to the smaller end of a large 
gelatin capsule (Parke, Davis & Co. "No. 12 Veterinary"). 
Remove any gelatin from the lumen of the tube, and paint 
the joint with a moderately thick celloidin. When dry, dip 
the capsule in thin celloidin beyond the junction with the 
glass tube, and rotate in the air until dry, to obtain an even 
coating. Do this repeatedly until a coating of the desired 
thickness is obtained. When thoroughly dry, apply thicker 
celloidin to the joint, to the other pole of the capsule, and 
to the line of junction of the two portions of the capsule, 
and allow to dry thoroughly. The gelatin is then to be 
removed by filling the capsule with water with the aid of a 
small Pasteur pipet and placing the capsule in boiling water 
for a few minutes, after which the melted gelatin and water 
is removed with the pipet. The sac is then filled with 
bouillon and placed with the glass tube downward in a test- 

1 Journal of Medical Research, vol. vii., pp. 202-212. In this paper there 
are also described forms of warm stages and the method of using them. 

2 Centralbl. f. Bakt., I. Abth., Orig. 1902, vol. xxxii., p. 74. 



I ID PATHOLOGICAL TECHNIQUE. 

tube containing sufficient bouillon to cover the sac to the 
depth of I cm., and the whole sterilized five minutes in the 
autoclave or in the Arnold steam sterilizer in the usual 
manner. Before placing the bacteria in the sac, some of the 
bouillon is removed under aseptic precautions by means of 
a pipet, so that a small empty space in the sac results. The 
bacteria are introduced with a pipet and the glass tube, 
grasped by sterile forceps near the junction with the sac, is 
sealed off in the small flame of the blast-lamp. The sac is 
then washed in sterile water and placed in a bouillon culture- 
tube and incubated overnight to test its permeability for 
bacteria. If the bouillon outside of the sac remains sterile, 
the sac is then ready to be placed in the peritoneal cavity oi 
the animal. 

3. THE INOCULATION OF ANIMALS. 

The animals ordinarily used in the laboratory are guinea- 
pigs, rabbits, and mice. The instruments, etc. used in the 
inoculation of animals should be sterilized beforehand, but 
strict surgical asepsis is not necessary as a rule. 

Guinea-pigs are in most instances inoculated either sub- 
cutaneously or into the peritoneum. 

Subcutaneous inoculation is effected either by injection with 
a hypodermic syringe or by the introduction of the material 
to be inoculated through a small incision in the skin. The 
best point for subcutaneous inoculation is the tissue of the 
anterior abdominal wall. 

In inoculating, the animal is to be held abdomen upper- 
most by an assistant, who grasps the neck and fore quarters 
with one hand and the hind quarters with the other. If the 
skin is to be incised, the hair about the point of inoculation 
is to be cut short with a pair of scissors and the skin cleansed 
with soap and water. An incision is then to be made about 
8 or 10 mm. long through the skin, including the subcuta- 
neous tissue, and the superficial tissues separated from the 
muscle for a distance of 10 or 15 mm. toward one side of 
the wound by inserting the points of scissors or other in- 
strument, so as to form a "pocket" beneath the skin. In 



BACTERIOLOGICAL METHODS. II J 

this " pocket" the material for inoculation is introduced, 
either on the platinum wire (see page 96) or by means of 
small forceps. 

If pieces of tissue are used, it may be well in some cases 
to close the wound by one or two sutures in order to pre- 
vent the extrusion of the material after the release of the 
animal. 

Intraperito7ieal inoculation may be performed essentially as 
above indicated. If the inoculation be by incision, the open- 
ing into the peritoneal cavity should be as small as possible, 
and the wound should be firmly closed with silk sutures in 
order to prevent extrusion of the intestines. 

In inoculating with the hypodermic syringe the needle 
should not be pushed in too far or the intestines may be 
wounded. The needle is best introduced a little to one side 
of, or slightly below, the umbilicus. 

Rabbits. — These animals may be inoculated both sub- 
cutaneously and intraperitoneally, essentially as described for 
guinea-pigs. 

In lifting or in carrying rabbits from one place to another 
the animals are to be grasped by the ears. During the ope- 
ration of inoculating, the assistant grasps the ears with one 
hand and the hind legs with the other, while the body of the 
animal rests upon the table, abdomen uppermost. Rabbits 
held for a few seconds in this position usually become per- 
fectly quiet, and often do not show any evidence of pain 
during the operation. 

Intravenous inoculation is usually done on rabbits, because 
of the ease with which the needle of a hypodermic syringe 
may be introduced into the long and prominent marginal 
vein of the ear. In inoculating in this manner the tip of the 
ear is held by the thumb and fingers of the left hand, while 
the right manipulates the syringe, the needle of which is 
pushed through the skin of the external surface of the ear 
into the vein which runs along the outer margin of the ear 
(Fig. 22). 

By the exercise of care and gentleness the animal may be 
thus inoculated without being held by an assistant, especially 



n8 



PA THOL O GICA L TE CHNIQ UE. 



if the fur between the ears be stroked for a short time just 
before the introduction of the needle. In some cases it may 
be necessary to anesthetize the animal on account of violent 
struggling. (See below.) 

Injection of bacteria into the mesenteric veins by means of the 
hypodermic syringe, after laparotomy, may be performed both 
on rabbits and on guinea-pigs. This is to be done under anes- 
thesia. Ether is very satisfactory for this purpose. Guinea-pigs 
bear it well, but it is to be used with caution on rabbits. With the 
latter animals death is liable to occur if the ether is " pushed ' ' after 




FlG. 22. — Method of making an intravenous injection into a rabbit. Observe 
that the needle enters the posterior vein from the hairy surface (McFarland). 

complete anesthesia is established. Rabbits once thoroughly anes- 
thetized seem to remain so for a considerable time without addi- 
tional ether being necessary. The incision for this form of inocu- 
lation should be in the lower half of the abdominal wall in the 
median line, for in this region the coils of the small intestine are 
most numerous. The length of the incision should be about 2 
cm. Several loops of intestine are brought out through the 
wound, and a mesenteric vein, of the proper size to admit the 
needle of a hypodermic syringe, is sought for. When found the 
needle is to be introduced and held firmly in position while an 
assistant carefully presses inward the piston of the syringe. After 
the injection of the material the needle is withdrawn, the punc- 
tured vein picked up with the artery- forceps, and the vessel tied 
on both sides of the puncture with silk thread. The loops of the 



BACTERIOL O GICAL ME THODS. 



II 9 



intestine are then replaced and the wound closed in two layers, 
one consisting of the muscles and peritoneum, the other of the 
skin. The so-called "button-hole stitch" with silk thread is 
very well fitted for the closing of the wound. 

Little or no aseptic precautions are necessary to obtain primary 
union in the wound. Before the operation, however, the hair of 
the region should be cut off close and the skin cleansed with soap 
and water. 

This form of inoculation may be useful in studying the local 
effects of bacteria upon liver-tissue, for large numbers of them 
will be lodged in the capillaries of the liver, and microscopical 
sections of any part of the organ will contain them, so that any 
local lesion produced by them may be subjected to observation 
after variable intervals of time. 

Mice are usually inoculated subcutaneously at the root 
of the tail. The animal, manipulated by means of chemists' 
crucible tongs or a similar instrument grasping his tail, is to 
be persuaded to crawl into a cylinder of wire gauze, about 




Fig. 23. — Mouse-holder, with mouse in position for inoculation.' 

8 to 10 cm. long and about 3 cm. in diameter, which is fixed 
on a small board. The cylinder is open at both ends, and 
when the mouse has crawled into it — a thing which he will 
readily do — the end near his tail is bent inward so as to pre- 
vent him from backing out of it, while an ordinary small 
screw-clamp is adjusted firmly to his tail to prevent his es- 
caping through the other end. The animal is thus secured 
and ready for the operation of inoculation. A more com- 
plete form of this apparatus, with a fixed clamp for the ani- 
mal's tail, is shown in Fig. 23. 



120 PATHOLOGICAL TECHNIQUE. 

In making the inoculation the mouse is pulled backward 
by the tail until his rump is exposed in the end of the cylin- 
der, and then with small scissors the hair is cut away over a 
space, approximately I cm. square, about the root of the 
tail. In the center of this a small opening is made through 
the skin 3 or 4 mm. long with small scissors, and through 
the opening the points of the scissors are passed anteriorly 
beneath the skin for a distance of about 1 cm., so as to make 
a " pocket " or cavity by separating the skin from the mus- 
cles. Into the cavity thus formed the material for inocula- 
tion is then to be introduced by means of the platinum wire. 
As a rule, white mice are to be preferred to the wild brown 
variety, on account of the greater ease with which they may 
be handled. 

Mice may also be inoculated in the peritoneal cavity by intro- 
ducing a very few drops of a suspension or a bouillon culture 
of an organism with a hypodermic syringe. 

The quantity of bacteria used for purposes of inoculation 
varies with the organism and with the end in view. In gen- 
eral, it may be said that in inoculating with the growth from 
a solid medium with the platinum wire one or two loopsful 
are used. If bouillon cultures are employed, the quantity 
injected varies from -^ c.c. to 1 c.c. in most cases. 

In cases where a " suspension " of the growth on a solid 
medium is injected the same quantities are used as in the 
case of bouillon cultures, the density of the suspension de- 
pending upon the operator. A " suspension " may be con- 
veniently prepared by pouring 5 or 8 c.c. of sterile bouillon, 
sterilized water, or 0.6 per cent, sodium chlorid solution (ster- 
ilized) into the tube containing the growth upon solid medium, 
then breaking up the colonies of the growth with the plat- 
inum wire, and shaking the tube. 

The Care of Animals. — Inoculated guinea-pigs should 
be kept in boxes or cages so arranged as to permit of clean- 
ing and disinfection. Cages made of a combination of gal- 
vanized-iron wire netting and galvanized sheet iron are 
to be preferred. The bottom of the cage should contain 



BACTERIOLOGICAL METHODS. 121 

sawdust, and the top may be made to open ou hinges. Good 
dimensions for such cages are 16 inches long, 10 inches 
wide, and 10 inches high. They may be satisfactorily dis- 
infected, in most instances at least, by washing with boiling 
water. 

Inoculated mice are well kept in large glass jars with per- 
forated covers. A small amount of raw cotton should be 
provided for bedding. 

The "stock" guinea-pigs and rabbits may be kept together 
in a pen which should have light and ventilation. Guinea- 
pigs breed readily and their young thrive, but this is not 
usually the case with rabbits. Mice may be kept for use in 
a woven-wire cage set in a sheet-iron pan, which will permit 
of the easy removal of excreta. Some raw cotton should be 
furnished for bedding. The young of white mice are diffi- 
cult to raise to maturity. 

Food. — Rabbits and guinea-pigs eat the same things. In 
summer-time, grass, green corn-husks, and green vegetables 
generally are good food for them. In winter, carrots and oats 
form a satisfactory diet. Fresh water should also be supplied. 

Mice may be fed on stale bread soaked in water, oats, bird- 
seed, and occasionally some cheese. Fresh water should be 
furnished, and, if possible, a little milk sometimes. 

4. CULTIVATION WITHOUT OXYGEN (ANAEROBIC CUL= 

TURES). 

Of the numerous methods and modifications of methods 
that have been proposed for the cultivation of anaerobic 
bacteria, only those are given here which have worked suc- 
cessfully in our hands, or are regarded as the simplest and 
most practical. 

Culture-media for Anaerobic Bacteria. — The agar- 
agar, gelatin, or bouillon used for the cultivation of ana- 
erobic bacteria should contain I per cent, glucose. These 
media should not be more than two weeks old for the best 
results. 

Their reaction is of the greatest importance, and should 
be adjusted by titration (see page 83). In the case of gel- 



122 PATHOLOGICAL TECHNIQUE. 

atin and of agar-agar the reaction should be I per cent, or 
1.5 per cent, of normal acidity to phenolphthalein. In the 
case of glucose bouillon, however, a more rapid growth 
is obtained with a reaction of less than 1 per cent, normal 
acidity to phenolphthalein. A degree of acidity greater than 
this is probably a frequent cause of failure to obtain cultures 
of obligate anaerobes in bouillon. Therefore, it is of the 
utmost importance, in working with glucose bouillon, to be 
sure that it has the proper reaction at the time of its use. 

The culture-medium must be thoroughly boiled imme- 
diately before inoculation in order to expel absorbed oxygen. 
It is then to be cooled rapidly by immersing the tube in cold 
water, and is to be inoculated within a few minutes after- 
ward. 

Method of Liborius (Fig. 24). — This consists in culti- 
vating the bacteria in the depths of solid media in test-tubes 
filled to a considerable height, so that oxygen cannot pene- 
trate to them through the thick layer of medium. 

A test-tube is filled about three-quarters full l of sterile glu- 
cose gelatin or glucose agar-agar, and its contents boiled for 
a few minutes to expel the excess of oxygen from the me- 
dium. The tube is then immersed in cold water to cool its 
contents rapidly, and then, before the medium becomes solid, 
the tube is placed in a water-bath at 38 to 40 C. for a 
few minutes. When the medium may be assumed to have 
reached this temperature, it is inoculated with the material 
from which a growth is sought to be obtained, and then 
rapidly solidified in cold water. The colonies of anaerobic 
bacteria develop only in the deeper layers of the culture- 
medium. These colonies may be made accessible for sub- 
cultures either by breaking the tube or by removing the 
overlying portions of the culture-media by means of a stout 
platinum wire, previously sterilized in a flame. For taking 
out colonies for transplantation, a capillary glass tube, ster- 
ilized in a flame, may be found useful in place of the pla- 
tinum wire. In inoculating the tube, care should be taken 
to secure a good distribution of the bacteria through the 
medium by manipulating the platinum wire. 

1 The tube need not be filled more than half its length. 



BA CTERIOL O GICAL ME THODS. 



23 



This method will be found very practical for obtaining 
pure cultures from mixed growths if dilutions (see page 1 10) 
be made. In making dilutions it is well to use a tube of 
bouillon or sterilized water for the first tube, thus econo- 
mizing medium, for the first tube will usually have so many 
colonies that no colonies suitable for sub-cultures will be 
available. 

The microscopical appearances of the colonies may be 
studied by placing thin slices of the medium, containing 



Fig. 24. — Liborius's method of 
making anaerobic cultures. 



Fig. 25. — Buchner's method of 
making anaerobic cultures. 



the colonies, on a slide. These slices may be easily ob- 
tained with the aid of a stout platinum wire with a flattened 
end, more or less bent. 

Anaerobic bacteria grow readily in " deep stab " cultures. 
In these cultures the medium should fill the tube to almost 
half its height at least. After inoculation some melted 
medium may be poured in so as to fill the tube to an addi- 
tional height of some centimeters, but this is not necessary. 

Esmarch's Method. — This consists in preparing an Es- 
march roll-culture (see page 112), of the organism, and, while 
the layer of glucose gelatin is still cold from the ice, filling 
the tube with liquefied gelatin and solidifying this rapidly in 



124 PATHOLOGICAL TECHNIQUE. 

cold water. The end of the tube is then to be sealed air- 
tight. The colonies develop in the layer of gelatin close to 
the side of the tube, and thus can be readily studied with 
low magnifying power. 

Simple Anaerobic Plate-cultures. — These are prepared 
like the ordinary Petri plate-cultures (see page no) except 
that the melted culture-medium is poured into the upturned 
larger dish, or cover, of the pair, while the smaller dish is 
then placed, bottom surface downward, in the melted culture- 
medium, and allowed to settle by its own weight into the 
fluid medium. The dishes are not disturbed until the 
medium has hardened. Sufficient medium should be used 
to fill the space between the sides of the dishes. This quan- 
tity will be about 10 c.c. By slightly inclining the smaller 
dish in placing it in the melted medium, air-spaces can be 
easily avoided. 

By this method the colonies develop in a thin layer of 
culture-medium enclosed between glass surfaces. The 
method gives a good chance to study the microscopical 
characters of the colonies. Surface colonies are, of course, 
not obtained by this method. The colonies are easily made 
accessible for transplantation by separating the dishes from 
one another. The layer of culture-medium will adhere to 
one dish or the other. 

In order to avoid contamination, the dishes should be 
arranged in the manner above described during their ster- 
ilization previous to using. 

Buchner's Method. — This method consists in cultivating 
bacteria in an atmosphere from which the oxygen has been 
absorbed by a mixture of alkali and pyrogallic acid. Tube- 
cultures, or cultures in Petri dishes, may be used. They 
should be placed in some form of a glass chamber, which is 
closed air-tight, along with the necessary quantity of alkali 
and pyrogallic acid mixture. In preparing the apparatus, 
the pyrogallic acid (in powder) is placed first in the chamber 
along with the culture tubes or plates, then the necessary 
quantity of a solution of potassium hydroxid (i : 10) is run 
in, and the chamber quickly closed. For single tube-cult- 
ures a large test-tube provided with a tightly-fitting rubber 



BACTERIOLOGICAL METHODS. I 25 

stopper, which is sealed in position with wax, may be used 
for the air-tight chamber (see Fig. 25.) The culture-tube is 
to be elevated above the surface of the reducing mixture by 
means of a bent wire. 

If a number of tube-cultures or Petri plate-cultures are 
desired, the glass chambers known as Novy's jars are very 
satisfactory to use. The joints of this apparatus should be 
well smeared with vaselin. To avoid breakage the test- 
tube containing the inoculated culture-medium may be held 
in a beaker, with some cotton at the bottom, while in the 
apparatus. Petri plate-cultures may be placed one above 
another in the jar, the bottom plate being supported above 
the level of the reducing fluid by some sort of wire frame. 

It is necessary to seal up the apparatus quickly in order 
to obtain the full benefit of the oxygen-absorbing power 
of the pyrogallic acid. The quantity of pyrogallic acid em- 
ployed should be about 1 gram for each 100 c.c. of air-space 
to be exhausted of oxygen, and for every gram of pyro- 
gallic acid 10 c.c. of the solution of potassium hydroxid 
should be used. 

Wright's Method. — The method depends upon the ab- 
sorption of oxygen by an alkaline solution of pyrogallic 
acid, as in the well-known method of Buchner. It is appli- 
cable to culture in test-tubes and in flasks. The details of 
the method are as follows : 

After the culture-medium in the test-tube has been inocu- 
lated, the cotton stopper is thrust sufficiently far down into 
the test tube so that the upper end of the cotton stopper 
lies about 15 mm. below the mouth of the test-tube. It is 
usually desirable to cut off a part of the protruding portion 
of the cotton before doing this. Now fill the space in the 
tube above the cotton stopper with dry pyrogallic acid. 
Next pour quickly onto this pyrogallic acid enough of a 
strong watery solution of sodium hydrate to dissolve it all ; 
avoid pouring on an excess ; for a test-tube -J of an inch in 
diameter about 2 c.c. will be an ample quantity. Then, as 
quickly as possible, insert firmly a rubber stopper in the 
mouth of the tube so as to close it tightly. The culture is 
then ready to be set aside for development. 



126 



PA THOL O GICAL TECHNIQ UE. 



The cotton of the stopper should be of a kind that will 

readily absorb fluids. 

The solution of sodium hydrate consists of one part of 

sodium hydrate in sticks and two parts of water. 

It may be thought that there is danger of contaminating 

the culture-medium from the alkaline pyrogallic acid mix- 
ture running down the sides of the 
tube. This does not occur, be- 
cause the mass of the cotton stop- 
per is sufficiently large to absorb 
completely the quantity of fluid in 
it, with a good margin to spare. 

This simple method has given 
satisfactory cultures of the tetanus 
bacillus obtained from cases of 
tetanus in the Massachusetts Gen- 
eral Hospital and of other obligate 
anaerobic bacteria. It can be ap- 
plied to all forms of test-tube cul- 
tures, both in solid and fluid media, 
including Esmarch roll-cultures. 
In applying the method to Esmarch 
roll-cultures the mixture of pyro- 
gallic acid and alkali should be 
placed in the cotton, and the rub- 
ber stopper inserted before the tube 
is rolled on the ice. Glucose-agar 
readily lends itself to Esmarch roll- 
cultures if the tubes are kept in a 




Fig. 26. — Wright's method 
for the cultivation of anaer- 
obes. 



slanting position during growth. 



The accompanying photograph 
shows the appearance of a bouillon 
tube prepared according to this method (Fig. 26). 

A Simple Method for Anaerobic Cultivation in Fluid 
Media (J. H. Wright). — The method here described has 
been successfully used for the cultivation of the tetanus 
bacillus and other obligate anaerobes. 

The apparatus consists of a simple arrangement of glass 



BACTERIOLOGICAL METHODS. 



27 



and rubber tubes enclosed in an ordinary test-tube with a 
plug of cotton inserted in its mouth as in an ordinary culture- 
tube. The construction of the apparatus will be plain from 
a consideration of Fig. 27. 

A is a glass tube somewhat constricted at each extremity ; 
B and C are short pieces of small rubber tubing; D is a 
glass tube in the upper extremity of 
which a small plug of cotton is in- 
serted ; E is a piece of rubber tubing. 
The test-tube contains a quantity of 
the culture-fluid as indicated by the 
figure. 

When it is desired to make an 
anaerobic culture, the fluid in the 
test-tube is inoculated in the usual 
way. The fluid is then sucked up 
into the system of glass and rubber 
tubes to a level above the rubber 
tube C. When it has reached this 
level, the rubber tube E is com- 
pressed between the fingers to pre- 
vent the down-flow of the fluid, and 
the system of tubes is then pushed 
downward in such a way as to bend 
the rubber tubes B and C in the 
manner shown in Fig. 28. If the 
test-tube and the inner tube system 
are of suitable size, the rubber tubes 
mentioned will remain in this bent 
position. The fluid in the tube A is 
thus contained in a water-tight space, 

1 1 11 i -r» 1 ^ Figs. 27, 28. — Wright's 

because the rubber tubes B and C, method of making ana6robic 
when bent to the angle shown in cultures in fluid media. 
Fig. 28, are thereby closed water- 
tight. That a flexible rubber tube does so close itself when 
bent to a certain angle is a matter of common observation. 

Cover-glass preparations may be made from the culture- 
fluid by straightening out the system of tubes and allowing 




128 PATHOLOGICAL TECHNIQUE. 

the fluid in them to flow out into the test-tube, where it is 
accessible to the platinum loop in the usual way. 

The advantages of this method are : 

i. Its simplicity and the easy construction of the appa- 
ratus. 

2. The possibility of keeping any number of pieces of 
the apparatus on hand sterilized ready for use as ordinary 
bouillon tubes are kept on hand. 

3. It offers a means of determining whether a given bac- 
terium grows better under aerobic or anaerobic conditions, 
by comparing the growth in the fluid outside in the test-tube 
with the growth of the fluid in the inner tube A. 

4. It makes it possible for the user to form some idea of 
the purity or impurity of the culture with the naked eye, for 
if one is working with strict anaerobes the lack of bacterial 
growth in the fluid outside in the test-tube is a good sign 
of the absence of contamination with aerobic bacteria. 

In using this method it is, of course, necessary that most 
of the air in the culture-fluid be expelled before it is inocu- 
lated. This is easily done by boiling the culture-fluid over 
the flame of a Bunsen burner without removing the inner 
system of tubes, and then cooling the apparatus by placing 
it in cold water. 

The sterilization of the apparatus is effected by steam, care 
being taken that the rubber tubes be not bent in the position 
shown in Fig. 28 during the sterilization, for the heat may set 
them permanently in this position. 

Bouillon Cultures under Hydrogen. — These are prepared 
by displacing the air in an ordinary culture-tube or other 
vessel containing glucose bouillon by hydrogen, and her- 
metically sealing the tube. The bouillon-tube is closed by 
a rubber stopper through which two small glass tubes pass, 
one running to the bottom of the tube, the other extending 
just inside the rubber stopper. 

The tubes outside the stopper are bent at right angles, 
and then, beyond the bends, are constricted by drawing out 
while hot, so as to be readily sealed with the Bunsen flame. 
In the outer ends of the tubes loose plugs of cotton are 



BA CTERIOL O GICAL ME THODS. 



2 9 



placed, and the apparatus thus prepared is sterilized by 
steam for half an hour. After sterilization and cooling the 
bouillon is infected with the organism, the stopper and its 
glass tubes being removed and replaced with care to avoid 
contamination. The stopper is then sealed in position with 
paraffin or sealing-wax, after which hydrogen from a hydro- 
gen generator is passed through the longer tube leading into 
the bouillon, and thus displaces the air through the shorter 
tube. After the hydrogen has flowed for 
five minutes the glass tubes are quickly 
sealed with the Bunsen flame at the con- 
strictions, and the culture thus prepared 
placed in the incubator. In passing the 
hydrogen through the apparatus the cotton 
plugs must of course be kept in position. 

The generation of hydrogen is best effected 
by means of the well-known apparatus of 
Kipp. It is important that no oxygen be 
present in the gas, or an explosion may occur 
during the sealing of the tubes in the Bunsen 
flame. 

Pure granulated zinc and pure sulphuric 
acid of 25 to 30 per cent, strength should 
be used. Before running the gas into the 
test-tube or other apparatus the reservoir of 
the generator should be allowed to fill with 
gas, and this then allowed to escape into the 
air by opening the outlet, care being taken 
that no flame be near by. This should be 
repeated, and then a sample of the hydrogen 
collected in an inverted test-tube by displacement of water in the 
well-known way. The same should then be ignited, and if no 
explosion occurs the hydrogen is fit to use. 

The hydrogen should be washed to insure the removal of im- 
purities from it by passing it through two washing-bottles before 
it is passed into the culture apparatus. One of these washing- 
bottles should contain an alkaline solution of pyrogallic acid, the 
other a 10 per cent, solution of acetate of lead. These may be 
easily constructed out of two large test-tubes provided with rub- 
ber corks through which the necessary glass tubes pass. 

Cultures under hydrogen on solid media may also be made 
in a manner similar to that described for bouillon cultures. 

An ingenious application of the method above described to 
9 




Fig. 29. — Frankel' s 
method of making an- 
aerobic cultures. 



130 PATHOLOGICAL TECHNIQUE. 

Esmarch roll-cultures under hydrogen is the so-called Prankel's 
method (Fig. 29). This consists in preparing dilutions in melted 
gelatin tubes, passing hydrogen through the melted gelatin in the 
tubes as in the case of bouillon, so as to displace all of the air, 
sealing the tubes, and then making Esmarch rolls on ice (see page 
112). While filling with the hydrogen the tubes are to be kept in 
a water-bath at about 35 ° C, in order that the gelatin may remain 
fluid. All of the precautions mentioned in the case of bouillon 
are to be observed in order to prevent contamination. 

Plate-cultures by Petri'' 's method, or ordinary tube-cultures, may 
also be grown by placing the plates or tubes in a vessel so con- 
structed that hydrogen may be passed into it until all the air is 
displaced, and the vessel is then hermetically closed. The appa- 
ratus of Novy, now on the market, is well adapted for this purpose. 

Before passing in the hydrogen a plug of cotton should be 
placed in each of the tubes of the apparatus, to prevent the access 
of bacteria to the interior. The entire apparatus should also be 
sterilized by steam before the plates are placed in position and be- 
fore the hydrogen is run in. 

The hydrogen should be passed through the Novy jar until a 
sample of the gas that issues from it is found to be free from 
oxygen by the test just described. Then the valve of the jar is 
to be closed for -five or ten minutes, after which time more hydro- 
gen is to be passed through the apparatus. When the outcoming 
gas has been proved to be free from oxygen, the valve is to be 
permanently closed and the apparatus set aside for development 
of the cultures. 

Cultures in Vacuo. — These are very satisfactorily made by 
placing the culture-tubes or culture-plates in the Novy jars 
together with an alkaline solution of pyrogallic acid, as described 
under Buchner's method, and then exhausting the air contained 
on the tubes by means of a water- vacuum pump such as chemists 
use. The pyrogallic acid will thus absorb the oxygen which 
cannot be removed by the pump. The Novy jars are very good 
to use for this purpose, because they are provided with suitable 
air-tight valves. 



IV. SPECIAL BACTERIOLOGY. 

The number of species of bacteria of pathogenic signif- 
icance which are commonly encountered in pathological pro- 
cesses in man is a small one. These comprise the staphylo- 
coccus pyogenes aureus, the streptococcus pyogenes, the 
pneumococcus, the bacillus coli communis, the typhoid ba- 
cillus, the bacillus diphtheriae, and the bacillus tuberculosis. 



BACTERIOLOGICAL METHODS. 131 

It is with infections with these few species that the patholo- 
gist is most frequently concerned, and the determination of 
the presence of these alone comprises by far the greater part 
of the bacteriological work which he is called upon to do. 

In the following descriptions of the important pathogenic 
bacteria which are concerned in human pathology the main 
object will be to give those characteristics which will serve 
for their identification, rather than an exhaustive consideration 
of their various properties and modes of growth. 

Staphylococcus Pyogenes Aureus. 1 — The colonies 
on blood-serum are golden yellow in color. They are 
rounded, shining, slightly elevated, and may attain a diam- 




••: 






Fig. 30. — Staphylococcus pyogenes aureus from a culture ; X 2000 (Wright and 

Brown). 

eter of 2 mm. or more after remaining for, thirty-six hours in 
the incubator. The color of the colonies varies from a pale 
yellow to a deep orange. Young colonies may be creamy 
white, becoming yellow later. 

Morphology. — Rather small cocci, frequently arranged in 
masses or clumps. 

Stained by Gram's method. 

1 J. Rosenbach : Mikroorganismen bei den Wundinfectionskrankheiten des 
Menschen, Wiesbaden, 1884. 



132 



PA THOL O GICA L TE CHNIQ UE. 



Gelatin Stab-culture. — Growth along the line of stab, fol- 
lowed by liquefaction in funnel form, with yellow sediment 
and clouding of the liquefied medium (Fig. 31). 

Potato. — Yellow confluent colonies. 

Agar-agar Slant. — Rather broad shining streak with 
sharply defined margins, at first white in color, but later 
becoming yellow. 

Bouillon. — Densely clouded. A yellowish sediment is 
formed, and sometimes a thin pellicle is seen on the surface. 



Fig. 31. — Staphylococcus pyogenes aureus: stab-culture three days old in gek 
tin (Frankel and Pfeiffer). 



Litmus-milk. — Turned pink and coagulated. 

Pathogenesis. — When inoculated into the circulation of a 
rabbit death follows in from eighteen hours to three days in 
the case of virulent cultures. Not all specimens of this 
organism are virulent. The lesions produced in the rabbit 
by inoculation in the ear-vein in typical cases are abscesses 
with infarctions in the kidneys, and miliary abscesses in the 



BACTERIOLOGICAL METHODS. I 33 

myocardium, diaphragm, and voluntary muscles. In the 
kidneys lines of necrosis with purulent infiltration, mainly in 
the pyramids, are frequently observed. This organ is the 
one most constantly affected. The number and extent of 
the lesions vary in different animals and with different cul- 
tures. They are best developed in animals which survive 
about three days. In animals which succumb after eighteen 
hours no macroscopic change may be apparent. On micro- 
scopical examination of the kidneys, however, small areas of 
necrosis will usually be found, mainly in the pyramids, sur- 
rounding masses of cocci. In the kidneys of animals which 
survive longer all the grades of invasion of these necrotic 
areas by leucocytes, up to regular abscess-formation, may be 
traced. By cultures the organism will be found in large 
numbers in the kidneys and urine of the rapidly fatal cases, 
and in smaller numbers in the other organs and blood of the 
heart. 

Occurrence. — The staphylococcus pyogenes aureus is found 
most commonly in pus-formations of a circumscribed cha- 
racter and also in a large number of pathological conditions, 
of which only the more important will be mentioned here. 

These are as follows : Osteomyelitis, peritonitis, pleuritis, 
endocarditis, meningitis, broncho-pneumonia, and puerperal 
septicemia. It may also be found in the blood of the various 
internal organs at autopsies in cases in which a suppurative 
or other acute inflammatory process is present anywhere, 
with or without metastatic abscess-formation. The organism 
also occurs frequently in the dust of places inhabited by 
man, as well as on the surface of the skin and of the mu- 
cous membranes of the nose and mouth. 

Diagnosis. — The staphylococcus pyogenes aureus cannot 
usually be identified with any certainty by the cover-glass 
examination alone. Cultures are necessary in order to dif- 
ferentiate from the other staphylococci and from the strep- 
tococcus. 

For practical purposes the identification of the pyogenic 
cocci may be made by the appearances of their colonies on 



134 PATHOLOGICAL TECHNIQUE. 

blood-serum and by their morphology ; no secondary cult- 
ures are usually necessary. 

The following staphylococci may also be present in acute 
inflammatory processes, but they occur less frequently than 
does the staphylococcus pyogenes aureus. 

Staphylococcus Pyogenes Albus and Staphylococcus 
Pyogenes Citreus. — These organisms differ from the staphylo- 
coccus pyogenes aureus mainly in the color of their colonies. 
As a rule, they are much less pathogenic for rabbits than that 
organism. 

Staphylococcus Epidermidis Albus (Welch). — " Is prob- 
ably only a variety of the staphylococcus pyogenes albus. Usu- 




FlG. 32. — Streptococcus pyogenes ; cover-glass preparation of the pus of an 
abscess ; x 1000 (Frankel and Pfeiffer). 

ally grows somewhat more slowly ; liquefies gelatin and coagulates 
milk less rapidly. Is of little virulence under ordinary conditions. 
Is a regular inhabitant of the epidermis, lying deeper than can be 
reached by disinfection of the surface of the skin" (Welch). 

Staphylococcus Cereus Albus. — Very similar to the staph- 
ylococcus pyogenes albus, but does not liquefy gelatin. May 
occur in abscesses. 

Staphylococcus Cereus Plavus. — This organism is similar 
to the preceding, except that it forms a lemon-yellow pigment. 

Streptococcus Pyogenes. 1 — This organism may be re- 

1 Rosenbach : loc. cit., p. 129. 



BA CTERIOL GICAL ME THODS. 



135 



garded as identical with the streptococcus erysipelatos of Feh- 
leisen. 1 

Blood-serum. — Minute grayish-white colonies, often look- 
ing like small grains of sand scattered over the surface of 
the medium. Sometimes the colonies are shining, trans- 
lucent, colorless, resembling minute dewdrops. 

Morphology. — Rather small cocci arranged in chains, each 
coccus being divided into two hemispheres by a line of 
division running at right angles to the axis of the chain 
(Figs. 32, 33). The chains may be made up of many cocci 
and be quite long. 



&\ 




t • 


\\ W r- 




lb/ / 


^ m m&®0 







FlG. 33.— Streptococcus pyogenes from a culture in bouillon ; x 2000 (Wright 

and Brown). 

Cover-glass preparations from the colonies often fail to 
show the characteristic chain arrangement, owing to the 
chains being broken up by the manipulation. The chain- 
formation is best demonstrated in cover-glass preparations 
from the " water of condensation " at the bottom of the 
blood-serum tube. This is essentially a bouillon culture, 
and it is in such fluid media that the chain-formation is best 
developed. In preparing the cover-glass from this as little 
manipulation of the fluid as possible should be used, in 
order to avoid destroying the chain arrangement. 

Practically, the only organism with which the strepto- 
coccus may be confounded is the pneumococcus, which also 

1 Fehleisen : Die Aetiologie des Erysipels, Berlin, 1SS3. 



I36 PATHOLOGICAL TECHNIQUE. 

grows in minute colonies and sometimes in chains. The 
streptococcus may be distinguished from the pneumococcus, 
however, by the morphology of the individual organisms, 
the streptococci appearing as pairs of hemispheres, and the 
pneumococci as pairs of oval, conical, or lancet-shaped or- 
ganisms, the broader ends of which are in apposition. 

Stains by Gram's method. 

Bouillon. — The character of the growth in bouillon is sub- 
ject to considerable variation, and certain doubtful varieties 
of the streptococcus are distinguished mainly by the bouil- 
lon culture. 

" We thus distinguish short-chained streptococci (' strepto- 
coccus brevis '), long-chained streptococci (' streptococcus 
longus '), streptococci which render bouillon cloudy and 
those which do not, streptococci which form flocculent or 
scaly or sandy or viscous sediments. 

" The name ' streptococcus conglomeratus ' is given to a 
streptococcus which grows, without clouding the bouillon, in 
the form of dense, separate particles, scales, or thin mem- 
branes at the bottom or sides of the tube, and on shaking 
the sediment it breaks up into little specks, without produ- 
cing uniform diffuse cloudiness. 

" On microscopical examination the chains in the latter 
case are long and interwoven in conglomerate masses. 
Streptococcus chains may be straight or wavy or twisted. 
These various distinctions are only of relative value. One 
form may change into another. Virulent streptococci may 
be found among all the groups mentioned ; the streptococci 
of erysipelas and most of the streptococci from abscesses 
and septicemia grow in long chains in bouillon " (Welch). 

Agar-agar Slant. — Minute grayish translucent colonies 

(Fig. 34). 

Agar-agar Stab. — Small spherical grayish colonies along 
the needle-track. 

Gelatin. — Growth similar to that on agar-agar. 

Litmus-milk. — Some varieties turn the medium pink and 
cause coagulation. 



BA CTERIOL O GICA L ME THODS. 



137 



Pathogenesis. — The results of the inoculation of animals 
are not constant, great variation in the virulence of dif- 
ferent cultures being observed. Some- 
times mice inoculated at the root of the 
tail or in the peritoneal cavity will die 
in about twenty-four hours with en- 
largement of the spleen and large 
numbers of the organism in the inter- 
nal organs. 

Occurrence. — The streptococcus oc- 
curs frequently in the spreading phleg- 
monous inflammations as well as in 
suppurative processes generally, and 
is the most common cause of septice- 
mia. It is almost always present in 
inflammatory conditions of the mucous 
membrane of the pharynx, and is often 
encountered in broncho-pneumonia. 
In erysipelas it is almost invariably 
the infecting organism, and it is the 
most frequent cause of puerperal sep- 
ticemia. In the majority of fatal cases 
of diphtheria and in some cases of 
typhoid fever, scarlet fever, tubercu- 
losis, and other acute inflammatory 
diseases it will be found in the blood 

of the various internal organs after death. It also occurs in 
a certain proportion of cases of peritonitis, pleuritis, men- 
ingitis, endocarditis, and otitis media. Gaining entrance to 
the tissues through an insignificant wound or abrasion of 
the skin, it may produce a rapidly fatal septicemia in a sus- 
ceptible individual, in whose internal organs at autopsy large 
numbers of the organism will be found. This general inva- 
sion of the circulation may also be observed in cases of 
chronic or wasting disease, the infection occurring during 
the last days or hours of life (terminal infection). 

Of other conditions in which it may occur, hepatic abscess, 
appendicitis, osteomyelitis, and synovitis may be mentioned. 




Fig. 34. — Streptococcus 
pyogenes : culture upon 
agar-agar two days old 
(Frankel and Pfeiffer). 



138 PATHOLOGICAL TECHNIQUE. 

Although the streptococcus is distinctly one of the pus-pro- 
ducing bacteria, yet the inflammations of the soft parts of 
the extremities which are produced by it are generally cha- 
racterized more by necrosis and serous or hemorrhagic exu- 
dation and infiltration than by the breaking down of tissue 
and frank pus-production. In this the organism is in marked 
contrast to the staphylococcus pyogenes aureus, which 
practically always produces dissolution of tissue and pus. 
Moreover, the streptococcus inflammations are more com- 
monly accompanied by lymphangitis than are those due to 
the staphylococcus pyogenes aureus. 

In a few instances we have met with a streptococcus whose 
colonies assume a well-marked yellow color on blood-serum, but 
which in other respects are like the long-chained forms above de- 
scribed. 

Diagnosis. — The streptococcus pyogenes may often be 
identified by the cover-glass examination alone through its 
characteristic chain-formation, but this may not be apparent 
and the result of cultures must then be awaited. 

Erysipelas. — The streptococcus is most readily found in 
the extreme margin of the affected area where the process is 
newest. The skin should be cleansed with soap and water, 
and with alcohol. Then with a sterile knife-point or a large 
needle a small wound should be made, and some of the 
blood and exudate pressed out from the tissue beneath. 
From this, cultures and cover-glasses may be prepared. 

Pnetimococcus. 1 — Synonyms : Diplococcus pneumoniae ; 
Micrococcus lanceolatus ; Micrococcus of sputum-septi- 
cemia ; Micrococcus pneumoniae crouposae. 

Blood-serum. — Minute colorless, transparent colonies, re- 
sembling very small drops of dew (Fig. 38). 

Morphology. — Pairs of rather small oval, conical, or lancet- 
shaped organisms, the broader ends being in apposition. 
The organism varies somewhat in size, and one of the " pair " 
may be smaller than the other (Fig. 35). In some cases 
atypical or involution forms are seen, especially if the culture 

1 A. Frankel: Zeitschrift fur klinische Median, Bd. x. u. xi. ; Weichsel- 
baum : Wiener med. Jahrbucher, 1886. 



BA CTERIOL O GICA L ME THODS. 



139 



be more than twenty-four hours old. No capsules are ordi- 
narily observed in cultures with ordinary methods of staining. 
In the " water of condensation " of the blood-serum tube, 
chains may be formed resembling those of the streptococcus, 




Fig. 35. — Pneumococci from a culture; X 2000 (Wright and Brown). 

but differing from the chains of that organism by the oval 

or lancet form of the elements of which they are composed. 

In pus, blood, or in other material, the organism is invested 

with a hyaline zone called the capsule (see Figs. 36, 37). 




FIG. 36. — Pneumococci with capsules in a cover-glass preparation from sputum 
stained by Gram's method and Bismarck brown ; X 2000 (Wright and Brown). 

This is composed of a mucin-like substance. It may be 
seen usually in cover-glass preparations stained by the ordi- 
nary methods, especially if the preparations be examined in 



140 PATHOLOGICAL TECHNIQUE 

Stained by Gram's method. Not motile. 

Glycerin Agar-agar. — Feeble growth of very minute gray- 
ish colonies. 

Bouillon. — Clouded faintly. 

Litmus-milk. — Sometimes turned pink and coagulated. 
Growth on other culture-media is very feeble. The organ- 




#* * 




Fig. 37. — Diplococcus pneumoniae ; cover-glass preparation from the heart's 
blood of a rabbit; X 1000 (Frankel and Pfeiffer). 

ism dies out rapidly in cultures. To keep it viable it should 
be transplanted every forty-eight hours. 

Pathogenesis. — The pneumococcus is very pathogenic for 
mice and rabbits, less so for guinea-pigs. 

Subcutaneous inoculation w r ith virulent cultures causes the 
death of mice in from twenty-four to thirty-six hours, and 
of rabbits in from thirty-six to forty-eight hours, with septi- 
cemia. 

This infection is the " sputum-septicemia " of Sternberg. 
At the autopsy there will be found in the blood everywhere 
the characteristic encapsulated lancet-shaped organisms, usu- 



BACTERIOLOGICAL METHODS. 141 

ally in pairs (Fig. 37). Great variation in the virulence of 
the organism is observed. In some cases no effect will be 
produced by the inoculation ; in others a more or less exten- 
sive fibrino-purulent exudation will be produced about the 
point of inoculation, and the animal will survive for a con- 
siderable length of time or recover. Inoculation into the 
ear-vein or peritoneal cavity of a rabbit will sometimes cause 
a rapidly fatal septicemia, when subcutaneous inoculation with 
the same culture will only cause a local reaction. The viru- 
lence of the pneumococcus is quickly lessened by cultivation. 

Occurrence. — The pneumococcus may be demonstrated in 
the pulmonary exudate of practically all cases of genuine 
lobar or croupous pneumonia. At autopsies on cases of this 
disease it may be found in large numbers in the consolidated 
lung, and sometimes in smaller numbers in the blood of 
other internal organs. Cultures from the lung may some- 
times show the presence of other bacteria in addition to the 
pneumococcus, but these are to be regarded as either second- 
ary infections or contaminations from the smaller bronchi. 

The pneumococci in the pneumonic exudate die in large 
numbers after a time, and in cases near resolution numerous 
capsules may be found in cover-glass preparations from the 
lung in which it is impossible to demonstrate the organism 
by staining methods. 

The pneumococcus is also frequently found in broncho- 
pneumonia, acute peri- and endo-carditis, acute pleuritis and 
empyema, acute purulent meningitis, and in otitis media. In 
cases of pneumonia and bronchitis it may be present in the 
sputum in large numbers. It has been observed in cases of 
peritonitis, of synovitis, of osteomyelitis, and of abscess-forma- 
tion in various situations. 

At autopsies on individuals dead of these conditions it 
may be frequently found, by means of cultures and animal 
inoculations, generally distributed throughout the internal 
organs in variable numbers. It is also often present in the 
mouth and in the saliva of healthy individuals. 

Diagnosis. — If the pneumococcus be present in very small 
numbers in "pathological material, the quickest and most 



142 PATHOLOGICAL TECHNIQUE. 

certain method of demonstrating its presence is the inocula- 
tion of a mouse with some of the material (see page 119). 
This is also the best way to prove the identity of the organ- 
ism. 

The pneumococcus can usually be identified in exudates, 
blood, tissues, or sputum by examination of cover-glass 
preparations alone, by reason of its peculiar morphology and 
its possession of a capsule. The capsule can be seen in most 
instances in cover-glass preparations, stained in the usual 
manner, if they be examined in water-mount. The capsules 
appear as a hyaline material usually with definite outlines 
surrounding the paired organisms. If it be desired to stain 
the capsules the following methods may be used. Their 
working is somewhat uncertain. 

Methods of Staining- the Capsule of the Pneumococcus. 
— Welch's Method. — This method depends upon the fact 
that acetic acid precipitates the mucin-like substance of 
which the capsule is composed, and that the precipitated 
material of the capsule is not soluble in a 2 per cent, solution 
of sodium chlorid. Therefore, any necessary washing of the 
preparation is to be done in the solution of sodium chlorid, 
and the mount is to be made in the same solution or in 
balsam. 

The method is as follows : 

1. Cover the preparation with glacial acetic acid for a few 
seconds. 

2. Drain off and replace (without washing in water) with 
aniline-gentian-violet solution. The staining solution is to 
be repeatedly added to the surface of the cover-glass until 
all of the acid is replaced. 

3. Wash in a 2 per cent, solution of sodium chlorid and 
mount in the same. 

W. H. Smith's Method. — This has been found particu- 
larly useful in demonstrating the pneumococcus in the 
sputum. The sputum or other material should be fresh. 
The cover-glasses should be spread as thinly as possible and 
fixed by passing three times through the flame in the usual 
manner. 



BACTERIOLOGICAL METHODS. 143 

1. Stain in aniline-gentian-violet solution for a few 
seconds, gently warming until the staining fluid steams. 

2. Wash in water. 

3. Cover with Gram's solution of iodin for thirty seconds. 

4. Wash with 95 per cent, alcohol until the color ceases 
to come out. 

5. Wash with ether for a few seconds. (To remove fat.) 

6. Wash in absolute alcohol for a few seconds. 

7. Stain one to two minutes in a saturated aqueous solu- 
tion of eosin. 

8. Wash with absolute alcohol for a few seconds. 

9. Clear with xylol. 
10. Mount in balsam. 

The pneumococcus is stained blue-black, while the capsule 
is stained pink. This method gives beautiful preparations. 
With the following modification it has been used by Smith as 
a routine stain for sputum. The advantage of this modifica- 
tion is that influenza bacilli and other bacteria which do not 
stain by Gram's method are clearly brought out, as are also 
eosinophilic leucocytes. This modification consists in wash- 
ing the preparation with Loffler's alkaline methylene-blue 
solution just after it has been stained with eosin, as described 
above, and then, after the excess of eosin has been removed 
by the methylene-blue, steaming the methylene-blue solu- 
tion for a few seconds while on the cover-glass. The prepa- 
ration is then washed in water, rinsed with alcohol, cleared 
with xylol, and mounted in balsam. 

Streptococcus CapSUlatus. — This seems to be the best 
name to apply to a capsule-bearing bacterium resembling 
both the pneumococcus and the streptococcus pyogenes in 
morphology, but differing definitely from them in cultural 
and other peculiarities. It has been found chiefly in lobar 
pneumonia, but occurs in other inflammatory processes and 
probably has been sometimes mistaken for the pneumococcus 
or the streptococcus pyogenes. The lack of general recog- 
nition of this micro-organism as a separate and distinct 
species vitiates, to some extent, the value of statistical studies 
of infections with the streptococcus and the pneumococcus. 



144 PATHOLOGICAL TECHNIQUE. 

The best description of the streptococcus capsulatus is 
that of Oscar Richardson, 1 based upon observations on 
4 cases of lobar pneumonia in the laboratory of the Massa- 
chusetts General Hospital. Richardson points out the fol- 
lowing chief characteristics by which it may be distinguished 
from the pneumococcus and the streptococcus pyogenes : 




Fig. 38. Fig. 39. Fig. 40. 

Fig. 38. — Pneumococcus ; blood-serum culture. 
Fig. 39. — Streptococcus capsulatus ; blood-serum culture. 
Fig. 40. — Streptococcus capsulatus; glucose-agar stab culture (Oscar Rich- 
ardson; photos by L. S. Brown). 

1. The capsules persist in cultures (see Fig. 41). 

2. On the surface of coagulated blood-seium its colonies 
are flat, colorless, viscid, mucus-like, of irregular outline, 
and may attain a diameter of 2 or 3 mm. They may become 
confluent and form large patches of mucus-like material (see 

Fig- 39)- 

3. In glucose-agar stab, adjusted to a reaction of 0.5, there 
is growth all along the line of inoculation, from which, in 

1 " Pseudopneumococci in Lobar Pneumonia," Journal of Boston Society 
of Medical Sciences, vol. v. , No. 2, p. 499. 



BA C TERIOL O GICA L ME THODS. 



H5 



places, fusiform or hemispherical masses of growth extend 
into the surrounding medium in a vertical plane, apparently 
occupying clefts in the medium (Fig. 40). It is very im- 
portant for the development of these characteristic appear- 
ances that the glucose-agar be known to have at the time 
of inoculation a reaction very close to that above indicated. 




Fig. 41 



•Streptococcus capsulatus from culture (Oscar Richardson; photo by 
L. S. Brown). 



GotlOCOCCUS. 1 — Morphology.— Coca, of medium size, com- 
posed usually of two hemispheres separated by a narrow 
unstained interval. Sometimes two of these pairs of hemi- 
spheres are joined together in the manner of " tetrads," or 
groups of four, showing evidence that division occurs in two 
directions at right angles to each other (Fig. 42). Decolor- 
ized by Gram's method. 

The gonococcus will not grow satisfactorily upon any of 
the culture-media ordinarily employed, but requires special 
media for its cultivation. 

The colonies on suitable culture-media appear after eigh- 
teen to twenty-four hours as minute, grayish, translucent 
points. Later they may attain a diameter of 2 mm. Under 

1 Neisser : Centralbl. f. d. vied. Wissenschaften, No. 28, 1S79 ; Bumm : Der 
Mikroorganismus der gono> rhoischen Schleimkauterkrankungen — '• Gonococcus 
Neisser, 1 ' Wiesbaden, 1887 ; Wertheim : Archiv f. Gynakologie, Bd. 4 2, 1892. 

in 



I46 PATHOLOGICAL TECHNLQUE. 

low magnifying power a well-developed colony is seen to 
consist of a generally circular expansion, with thin, trans- 
lucent, sharply defined margins, becoming brownish, granu- 
lar, and denser toward the center, which is made up of coarse 
brownish clumps closely packed together (Fig. 43). 

Special Culture-media. — The essential constituent of 
culture-media upon which the gonococcus will grow seems 



* 


« 


• 

» 








t ■ 

#• * 


9 

# 


• 


* 

f 


* 





Fig. 42. — Gonococci from a culture, showing formation of tetrads and variability 
in the size of the cocci; X 2000 (Wright and Brown). 

to be the blood-serum or similar albuminous fluid from the 
animal body. 

Probably the most convenient culture-medium for the 
cultivation of the gonococcus is hydrocele-flidd agar. This 
medium consists of sterile hydrocele fluid mixed with fluid 
agar-agar at a temperature of 40 C, in the proportion of 
1 part of hydrocele fluid to 2 or 3 parts of agar-agar. The 
hydrocele fluid is to be obtained under the strictest precau- 
tions to avoid contamination with bacteria, thoroughly ster- 
ilized vessels, etc., being used. 

Ordinary tubes of plain agar-agar (2 per cent.) which have 
been previously sterilized in the usual manner are melted and 



BA C TERIOL O GICA L ME THODS. 



1 47 



brought to a temperature of 40 ° C. in a water-bath. To the 
fluid agar-agar in each tube the sterile hydrocele fluid is then 
added in the proportion of one-third to one-half the volume 
of the agar-agar, care being taken to avoid contamination. 
For the transfer of the serum to the agar-agar tubes a steril- 
ized pipette may be used. The tubes may then be infected 
and their contents poured into sterilized Petri dishes, as in 
the plate method previously described (see page 1 to), or the 
tubes may be placed on their sides in a slightly inclined 
position and the agar-agar allowed to solidify, thus forming 
" slants " which may be kept on hand ready for use. In 







Fig. 43. — Gonococcus colony (low magnifying power ; photo by L. S. Brown). 

order to test for the presence of contaminating bacteria in 
these slants, it is well to place them in the incubator for 
twenty-four hours after they have become solid, so that any 
bacteria which may be present in them will form colonies 
and manifest themselves. Some pathological fluids which 
are rich in albumin, such as the serous exudate of pleuritis, 
may be used in the place of the hydrocele fluid as above 
described. 

Occurrence. — The presence of the gonococcus may be 
demonstrated in the pus of acute gonorrhea and gonorrheal 
ophthalmia. It occurs also in a certain proportion of cases 



I48 PATHOLOGICAL TECHNIQUE. 

of purulent salpingitis. It has been found in peritonitis, en- 
docarditis, pericarditis, myocarditis, pleuritis, and arthritis, as 
well as in peri-urethral abscess, in abscess of the glands of 
Bartholini, and in other acute inflammatory processes. In a 
few cases of endocarditis it has been demonstrated in the 
blood during life. 

Diagnosis. — For practical purposes the gonococcus may 
be sufficiently identified in pus by cover-glass examination 
of the same. Cocci in the form of paired hemispheres 
chiefly situated within the pus-cells and decolorizing by 
Gram's method of staining maybe regarded as gonococci 
with a fair degree of certainty. 1 The fact that they decol- 
orize by Gram's method serves to distinguish them from 
the pyogenic staphylococci and streptococci, for these may 
also be present inside leucocytes, and may in some instances 
look like gonococci. The identification by this means is not 
beyond question. To make it more certain the isolation 
and study of the suspected cocci in cultures are necessary. 
In cultures, not only should the organism show the pecu- 
liarities of morphology, of staining, and of colony growth 
above described, but it should be rigidly determined that it 
does not grow on ordinary agar-agar. 

In making transplants to plain agar avoid carrying over 
any of the albuminous material of the special culture- 
medium, for this material may permit some growth of the 
gonococcus on the plain agar. 

In applying the test of decolorization by Gram's method, 
colonies not more than forty-eight hours old should be used, 
because Gram-staining cocci in older cultures may be more 
or less decolorized by this method. In proof of the neces- 
sity of cultures for confirming the identity of the gonococcus 
in certain instances we may state that we have met with a 
Gram-decolorizing coccus in an arthritis of the knee, clini- 

1 There is no trustworthy evidence that any other Gram-decolorizing micro- 
coccus than the gonococcus ever occurs in gonorrheal pus. F. T. Lord, work- 
ing in the laboratory of the Massachusetts General Hospital, examined by cul- 
tures the pus from 22 cases of gonorrhea, and in none could he find any 
Gram-decolorizing micrococcus other than the gonococcus. 



BA CTERIOL OGICAL ME THODS. 



149 



cally of gonorrheal origin, which, in cover-glass preparations 
from the exudate, was regarded as the gonococcus, but which 
was found not to be that organism by the study of it in 
cultures. 

If it is desired to obtain cultures of the gonococcus from 
the pus of gonorrheal urethritis, the case should not be more 
than of a few days' duration, because cases of longer dura- 
tion will usually show the presence of other bacteria whose 
colonies overgrow the feebly growing colonies of the gono- 
coccus. An organism which may be mistaken for the gono- 




FlG. 44. — Gonococci inside a leucocyte. Cover-glass preparation from gonor- 
rheal pus; X 2000 (Wright and Brown). 



coccus is a coccus growing in large milk-white colonies on 
all media, but staining by Gram's method. This coccus is 
frequently found in gonorrheal pus after the discharge has 
lasted several days. Other cocci also occur. 

The pus for culture purposes may be collected on a 
"«?wab," and the special culture-medium directly infected 
with this. The gonococcus retains its vitality in the pus 
on the swab for a number of hours, but care should be 
taken to avoid drying. 

In a certain proportion of cases of purulent inflammation 
of the oviducts, gonococci may be found and cultivated, as 



150 PATHOLOGICAL TECHNIQUE. 

above indicated. The majority of cases, however, will have 
sterile pus, while in a small percentage of cases the ordinary 
pyogenic cocci will be present. 

Cultures from the blood in cases of gonorrheal endocar- 
ditis may give positive results, and may be made as follows : 
A quantity of blood is withdrawn from the median vein of 
the arm of the patient by means of a sterilized antitoxin 
syringe, under aseptic precautions, and is mixed with fluid 
agar in the proportions and in the manner above described 




Fig. 45. — Micrococcus catarrhalis in smear from sputum (F. T. Lord; photo by 

L. S. Brown). 

for the preparation of tubes of hydrocele-fluid agar. The 
mixture is allowed to solidify in the tubes in the form of 
" slants," or Petri plate preparations are made from it. The 
tubes or plates are then placed in the incubator. The mix- 
ture of blood and agar obtained by this method forms a 
good medium for the growth of the gonococcus. 

Method of Staining" for G-onococci. — Prepare a cover- 
glass with the pus, spreading it thinly with the platinum 
wire. The practice of spreading a small drop of pus between 



BA C TERIOL O GICA L ME THODS. 



51 



two cover-glasses and drawing them apart is objectionable. 
After " fixing," stain the preparation by the following method : 

1. Stain with aniline-gentian-violet solution for thirty 
seconds, without heating. 

2. Wash in water. 

3. Cover the preparation with Gram's iodin solution for 
thirty seconds. 

4. Wash in water. 

5. Wash with alcohol (95 per cent.) until the color ceases 
to come out of the preparation. 

6. Wash in water. 

7. Stain in saturated aqueous solu- 
tion of Bismarck brown for thirty 
seconds. 

8. Wash in water and mount. 
This method is nothing but Gram's 

method and after-staining with Bis- 
marck brown. With it the gonococci 
are stained brown, and other pyogenic 
cocci stained blue-black. 

W. F. Whitney has suggested the 
use of a 1 per cent, aqueous solution 
of pyronin in place of the solution 
of Bismarck brown in step 7. The 
gonococci are stained red by the 
pyronin. 

Micrococcus Catarrhalis. — This 
micrococcus may be found in the 
sputum in inflammatory conditions of 
the respiratory tract and cannot be 
distinguished in its morphology and 




staining reactions 



from the gono- 



Fig. 46. — Micrococcus 
catarrhalis colonies on agar 
(F. T. Lord; photo by 
L. S. Brown 1. 



coccus or from the Diplococcus intracellularis meningitidis 
(Fig. 45). The appearances of its colonies on ordinary 
culture-media are, however, characteristic. They are large, 
white, of irregular outline, and have elevated central por- 
tions. They are friable, not viscid, and grow readily at 
room-temperature (Fig. 46). 



152 



PA THOL O GICA L TE CHNIQ UE. 



Micrococcus TetragentiS. 1 — The colonics are small, 
white, and elevated. Growth is slow. 

Morphology. — Micrococci arranged in fours, or "tetrads," 
held together by a gelatinous substance (Fig. 47). 

Stained by Gram's method. Not motile. 

Gelatin Stab. — Feeble growth in the form of minute spheri- 
cal masses along the line of stab with a small white, slightly 
elevated point at the surface of the medium. The gelatin 
is not liquefied. 








Fig. 47. — Micrococcus tetragenus in pus from a white mouse; X 615 (Heim). 

Agar-agar Slant. — Moist, glistening, grayish-white trans- 
lucent streak with wavy margins. 

Potato. — Growth is in the form of "a thick, irregular, 
slimy-looking patch." 2 The growth on agar-agar and on 
potato may be drawn into thin threads by the platinum wire. 

Pathogenesis. — Subcutaneous inoculation of mice and 
guinea-pigs may lead to a fatal septicemia or only a local 
pus-formation. Intravenous or intraperitoneal inoculation 
of rabbits may also produce septicemia and death. 

At autopsy the micrococci, arranged in tetrads, are found 
in the blood generally, but most numerously in the spleen. 
They can readily be demonstrated by cover-glass prepara- 
tions. 

1 Koch : Mitth. a. d. Kais. Gesundheitsamte, Bd. 2, 1884; Gaffky : Arch, 
f. klin. Chirurgie, Bd. 28. 

2 Abbott : Principles of Bacteriology. 



BACTERIOLOGICAL METHODS. I 53 

Occurrence. — " Found not infrequently in phthisical cavi- 
ties and sputum, occasionally in association with pyogenic 
cocci in abscesses connected with carious teeth and about 
the neck and jaws and middle ear, rarely in abscesses else- 
where. It has been considered to be non-pathogenic for 
man, but it has been found in pure culture in closed ab- 
scesses in man, and Viquerst has proved experimentally 
that it is capable of causing suppuration in human beings " 
(Welch). 

Diplococcus Intracellulars Meningitidis. 1 — Mor- 
phology. — Diplococci, occurring as paired hemispheres, 
separated by a well-marked unstained interval and showing 
considerable variation in size in cultures (Fig. 48). The 




Fig. 48. — Diplococcus intracellularis meningitidis from a culture, showing the 
tendency toward grouping in fours or tetrads ; X 2000 (Wright and Brown). 

larger forms are regarded as involution or degenerate forms. 
The organism shows a tendency to grouping in fours or 
tetrads. 

In cover-glass preparations from the meningeal exudate 
the diplococcus frequently is situated inside leucocytes, and 
sometimes within the nucleus (Fig. 49). The appearances 
are very much like those of gonorrheal pus. It is decolor- 
ized by Gram's method. 

Blood-serum. — The colonies appear after about twenty-four 
hours, and after forty-eight hours may attain a diameter of 
2 or 3 mm. They are round, colorless, shining, slightly 

1 Weichselbaum : Fortschritte der Medicine^ Bd. 5. 1887 ; Jaeger: Z.ci;- 
schrift fur Hygiene tind Infectionskrankheiten, Bd. 10. 1805 ; Councilman: 

Transactions of the Association of American Physicians, 1S97. 



154 PATHOLOGICAL TECHNIQUE. 

convex or flat, moist, and viscid-looking. They may be- 
come confluent. 

Agar-agar. — Round, flat, grayish, translucent, moist, shin- 
ing colonies, attaining a diameter of 2 or 3 mm. after twenty- 
four hours in the incubator. They may become confluent, 
and in a "slant" culture the growth appears as a grayish, 
translucent, moist, shining streak about 3 mm. in width, 




Fig. 49. — Diplococcus intracellularis meningitidis in polynuclear leucocytes of 
meningeal exudate (Jaeger). 

with smooth margins. Under a low magnifying power 
the colonies are homogeneous, semi-translucent, and not 
granular. 

Sugar-agar Stab-culture. — Feeble growth not extending 
all along the line of inoculation. 

Bouillon. — Medium slightly to moderately clouded. At 
the bottom of the tube a whitish sediment, which may rise 
as a viscid string when the tube is shaken. 

Potato. — Very feeble or doubtful growth, giving the sur- 
face of the potato a moist appearance at the most. 



BACTERIOLOGICAL METHODS. I 55 

Litmus-milk. — Growth without visible change in the me- 
dium. 

Gelatin. — Feeble growth. No liquefaction. 

Vitality. — The organism quickly dies out under cultiva- 
tion. It seems to survive somewhat better on blood-serum 
than on agar-agar, but cultures on the former only seventy- 
two hours old may be found no longer capable of growth 
after transplantation. 

Pathogenesis. — Intraperitoneal inoculation of guinea-pigs 
and rabbits gives very uncertain results. Mice are said to 
succumb to subcutaneous inoculation, with some invasion of 
the blood by the organism. 

Exceptionally, we have found that the intraperitoneal in- 
jection of a bouillon suspension of a twenty-four-hour 
blood-serum culture in the quantity of about I c.c. would 
kill guinea-pigs within forty-eight hours. 

At the autopsy there is an accumulation of a cloudy or 
blood-stained fluid in the peritoneal cavity, some little en- 
largement of the spleen, and some injection of the perito- 
neum. Microscopical examination of the exudate shows 
numerous leucocytes crowded with the diplococci (Fig. 50). 
The culture-test gives no evidence of general infection of 
the blood. 

Occurrence. — Found in the meningeal exudate of certain 
cases of epidemic cerebro-spinal meningitis. It is situated 
mainly inside the pus-cells, some of which may contain 
many diplococci. In some cases the presence of the organ- 
ism in the exudate may be difficult or impossible to demon- 
strate, and it is probable that it rapidly dies out. It has been 
found in the arthritis and in the pneumonia which sometimes 
accompanies the disease and in the nasal secretion. A gen- 
eral invasion of the circulation by the micro-organism does 
not occur. 

Diagnosis (see also section on Lumbar Puncture). — In 
exudates suspected of containing it, cover-glass preparations 
should be stained by the method for gonococci (see p. 1 50). 
The presence of micrococci, often in the pus-cells, decolor- 
ized by Gram's method, is sufficient for its identification in 



156 PATHOLOGICAL TECHNIQUE. 

the meningeal exudate as far as our present knowledge goes. 
Cultures are necessary if the material is from other sources 
than the meninges. It is claimed that the diplococcus may 
be found in the nasal secretion of cases of the disease. F. 
T. Lord, 1 working in the Massachusetts General Hospital, 
found the diplococcus intracellularis meningitidis of Weich- 
selbaum in the nasal secretion of one case without symp- 
toms of meningitis out of 21 cases which he examined by 
culture for bacteria. Because of the frequent presence of 




Fig. 50. — Diplococcus intracellularis meningitidis in leucocytes. Cover- 
glass preparation from peritoneal exudate in a guinea-pig; X 200 ° (Wright 
and Brown). 

the micrococcus catarrhalis in the respiratory tract, he con- 
cluded that organisms from the nose, resembling the men- 
ingococcus in morphology and staining reaction, " cannot be 
accepted as meningococci unless the diagnosis is confirmed 
by cultures and the differentiation of the colonies from those 
of other closely related diplococci." From a review of the 
literature he states that " the meningococcus has been thus 
proved to exist in the nasal secretion of one patient with 

1 Centralbl. f. Bakt. etc., I. Abth., Originale, Bd. 34, No. 7. 



BACTERIOLOGICAL METHODS. I 57 

and three patients without meningitis. Forty-nine other 
cases, recorded in the literature as nasal infection with men- 
ingococci, are not thus substantiated." The material for 
examination is best obtained with the platinum loop from 
the superior portions of the nasal cavities. 

Bacillus Diphtherise. 1 — Blood-scrum. — Round, elevated, 
smooth colonies of the color of the medium. They may attain 
a diameter of 2 mm. after forty-eight hours in the incubator. 

Morphology. — Bacilli varying markedly in size and shape, 
of irregular outline, and showing great variability in the 
staining of different parts of their protoplasm (^Figs. 51, 52). 




Fig. 51. — Diphtheria bacilli from a culture on blood-serum, stained by 
LofRer's methylene-blue solution, showing deeply stained points; X 2 °°° 
(Wright and Brown). 

The presence in a palely tinted rod of deeply stained 
granules and points, frequently situated at the extremities, 
and the occurrence of irregular forms, often club-like in shape, 
with a constriction in the middle, are appearances which are 
very characteristic of the bacillus when grown upon blood- 
serum and stained with Loffler's methylene-blue solution. 
Its morphology and staining peculiarities are so characteristic 
when cultivated upon blood-serum that the microscopical 
examination is in most cases sufficient for its identification. 

^Loffler: Mittk. a. d. Kais. Gesundheitsamte, Bd. 2, 1SS4 ; Roux and Yer- 
sin : Annates de T Inst i tut Pasteur, T. 2-4, 1S88-90. 



158 PATHOLOGICAL TECHNIQUE. 

When grown upon other culture-media than blood-serum, 
however, its morphology and staining peculiarities are not so 
characteristic, and they may vary markedly in different media. 

Stained by Gram's method. Not motile. 

Bouillon. — Grows usually in the form of fine grains at the 
bottom of the tube and adherent to the sides, the bouillon 
remaining clear or becoming slightly clouded. The reac- 






v>.,n5" :^ r 



/ 






w* %JH> 



Fig. 52. — Diphtheria bacilli from a culture on blood-serum, stained by 
Loffler's methylene-blue solution, showing long and irregularly shaped forms of 
the bacillus, as well as the irregularity of staining ; X 2000 (Wright and Brown). 

tion of the media rapidly becomes acid, but changes to alka- 
line after a variable length of time. 

Potato. — Growth not visible to the naked eye. The bacil- 
lus grows, however, to a certain extent, and usually assumes 
very atypical and irregular forms (involution forms). 

Agar-agar and Gelatin. — The growth on these media is 
slower and more feeble than upon blood-serum (Fig. 53). 
It presents nothing remarkable. 

Pathogenesis. — Subcutaneous inoculations of guinea-pigs 



BA C TERIOL O GICA L ME THODS. 



159 



are fatal in thirty-six to seventy-two hours in the case of 
virulent cultures. The lesions produced consist usually of 
edema, hemorrhage, and fibrino-purulent exudation about 
the point of inoculation in the subcutaneous tissue, hemor- 
rhagic enlargement of the lymphatic glands, congestion and 
edema of the lungs, hemorrhages into the suprarenal cap- 




FlG. 53. — Bacillus diphtherise ; agar-agar culture (photograph by Dr. Henry 

Koplik). 



sules, and less frequently necrosis of the liver and pleural 
effusions. Histological examination of the lymph-glands 
shows marked " fragmentation " of the nuclei of the cells, 
giving rise to numerous deeply staining globules of chroma- 
tin scattered throughout them. The bacilli are ordinarily 
found only about the point of inoculation, but cultures from 
the various organs will sometimes show the presence of the 
bacilli in some of them. 



l6o PATHOLOGICAL TECHNIQUE. 

Toxin- production. — The effects produced by infection with the 
bacillus diphtherial are due to the action of a so-called toxalbumin 
or " toxin " which the organism manufactures in its growth. The 
poisonous substance is produced in cultures. Its presence may be 
demonstrated by inoculating an animal with a small quantity of 
the filtrate, obtained by passing a bouillon culture some weeks old 
through an unglazed porcelain filtering apparatus, by which all 
the bacteria are removed from the fluid. 

The "toxin" is contained in solution in the nitrate. If this 
be fairly rich in "toxin," the injection of -^ c.c. subcutane- 
ously into a guinea-pig should lead to the death of the animal in 
three or four days with the various lesions above described. The 
local reaction, however, is not so marked as in the case of inocu- 
lation with the bacilli. With the ordinary bouillon the produc- 
tion of a great amount of " toxin " by the growth of the diph- 
theria bacilli in it is very uncertain. Theobald Smith has recently 
shown that this uncertainty is due to the presence of variable 
amounts of muscle-sugar from the meat used in the preparation 
of the bouillon, and that this substance prevents the accumulation 
of toxin. He has found that that bouillon yields the most toxin 
which has the least muscle-sugar in it. He prepares such bouillon 
as follows : " Beef infusion, prepared either by extracting in the 
cold or at 6o° C, is inoculated in the evening with a rich fluid 
culture of some acid-producing bacterium (I use temporarily 
B. coli) and placed in the thermostat. Early next morning the 
infusion, covered with a thin layer of broth, is boiled, filtered, 
pepton and salt added, and the neutralization and sterilization 
carried on as usual." This bouillon is placed in two 500 c.c. 
Erlenmeyer flasks, 250 c.c. in each flask. In these, cultures are 
made and kept for at least eight days in the incubator. After 
this time a fair amount of toxin may be assumed to have 
developed, and the contents of the flask are then filtered 
through a porcelain cylinder. A filtrate is to be regarded as 
containing a reasonable amount of toxin if yL- c.c, injected 
subcutaneously, kills a medium-sized guinea-pig in three days. 
The filtrate containing the "toxin" can be preserved by the 
addition of 0.5 per cent, pure carbolic acid. 

Occurrence. — The bacillus diphtheriae occurs in the local 
lesions in all cases of true diphtheria, in rhinitis fibrinosa, 
and in many cases of the milder forms of acute inflammation 
of the air-passages. It may persist in the mucous mem- 
brane of the throat and nose long- after convalescence has 
been established. 

In fatal cases of diphtheria the organism is nearly always 
present in the lungs, and it may be often found by culture- 
methods more or less generally distributed in compara- 



BACTERIOLOGICAL METHODS. l6l 

tively small numbers throughout the internal organs. In 
the majority of diphtheria autopsies an invasion of the blood- 
stream by the streptococcus pyogenes, and sometimes by 
other bacteria, may be demonstrated by cultures. The ba- 
cillus may also be found in company with other bacteria in 
ulcerated or excoriated surfaces on the skin, as well as in 
other suppurative processes, in individuals affected with 
diphtheria, and on the soiled linen of the patient. The in- 
fection of wounds with the bacillus diphtheriae has also been 
observed without coincident diphtheria. 

Diagnosis. — The bacteriological diagnosis of infection 
with the bacillus diphtheriae depends upon the characteristic 
morphology and peculiarities of staining, as well as rapidity 
of growth, which this organism presents when cultivated 
upon coagulated blood-serum. The identification by direct 
cover-glass examination of the exudate is very uncertain. 

The method is as follows : A blood-serum culture-tube is 
inoculated with a small amount of the material from the 
mucous membrane affected, and is placed in the incubator 
twelve to eighteen hours. After this length of time the re- 
sulting growth is examined by cover-glass preparations 
stained either with Loffler's methylene-blue solution or by 
one of the special methods given below. 

The bacillus diphtheriae, if present, may then be recog- 
nized and differentiated from other bacteria present in the 
preparation by its characteristic morphology and peculiarity 
of staining, described on page 157. The gross appearances 
of the culture present little that is characteristic, as a rule, 
and the main reliance is to be placed on the microscopic ex- 
amination. Early in the infection the greater part of the 
growth may be made up of the specific bacilli, but toward 
convalescence they fall into the minority. The ordinary 
forms of agar-agar culture are not suitable for use in the 
bacteriological diagnosis of diphtheria, owing to the com- 
parative feebleness of the growth of the organism on these 
media, and because of the fact that its microscopic appear- 
ances when cultivated on such media are not sufficiently 
characteristic. 
11 



1 62 PATHOLOGICAL TECHNIQUE. 

The material for culture is very conveniently obtained by 
means of sterilized cotton swabs. In collecting this material 
the swab is removed from its test-tube and touched to the 
affected areas of the mucous membrane of either the nose or 
throat. It is then to be gently rubbed over the surface of a 
blood-serum culture-tube, or it may be replaced in the test- 
tube and the inoculation of the culture-tube made later in 
the laboratory. In the latter case the inoculation should be 
made within an hour or two after the material has been col- 
lected, the infected swab meanwhile being prevented from 
drying by firmly replacing the cotton plug. 

In cases with membrane-formation the greatest number 
of bacilli are on the surface or in' the upper layer of the 
membrane, and the swab should therefore be touched to 
these portions rather than to the tissue beneath. 

Special Methods of Staining the Bacillus Diphtherise. — 

Owing to the fact that the bacillus diphtherias may be recognized 
by its peculiar morphology and characteristic staining in cover- 
glass preparations from its growth upon certain culture-media, as 
already pointed out, various special staining methods have been 
devised for accentuating and rendering more striking to the eye 
the peculiar deeply stained points and granules in the bodies of 
the individual bacilli, which have been referred to as of great im- 
portance in the identification of the organism. 

These special methods of staining are said to be of great advan- 
tage in cases where only a few specific bacilli may be suspected 
to be present among a large number of other bacteria. 

Neisser s Method. — i. Stain for one to three seconds in a solu- 
tion which is made as follows : i gram of methylene-blue (Grue- 
bler), in powder, is dissolved in 20 c.c. of 96 per cent, alcohol. 
To this add 950 c.c. of distilled water and 50 c.c. of glacial acetic 
acid, and filter. 

2. Wash in water. 

3. Stain for three to five seconds in a solution of vesuvin 
(Bismarck brown), made by dissolving 2 grams of the dye (in 
powder) in 1000 c.c. of boiling distilled water. 

4. Wash in water, and mount. 

The diphtheria bacilli stained by this method appear as pale 
brown rods bearing bluish-black granules, usually of oval shape 
and of a diameter somewhat greater than the rod. The majority 
of the bacilli show a granule at each end or at only one end, but 
not rarely three granules are present, one being near the middle of 
the rod. More granules than these are exceptional (see Fig. 54). 

The bacilli must have been grown on Lofrler's blood-serum 



BACTERIOLOGICAL METHODS. 1 63 

medium, coagulated at ioo° C. , and the culture must be at least 
nine hours and not more than twenty-four hours old. 

Hunfs Method. — 1. Stain in saturated aqueous solution of 
methylene-blue one minute without heating. 

2. Wash in water. 

3. Cover with aqueous solution of tannic acid, 10 per cent., for 
ten seconds. 

4. Wash in water. 

5. Stain in saturated aqueous solution of methyl-orange one 
minute, without heating. 

6. Wash in water. 

7. Dry, and mount in balsam. 



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Fig. 54- — Diphtheria bacilli from blood-serum culture stained accordmg to 
Neisser's method ; X 2000 (Wright and Brown). 

By this method the granules, etc., are dark blue or almost black, 
and stand out very sharply against the light-green coloring of the 
body of the bacillus (see Fig. 55). The solution of methyl-orange 
should be freshly prepared, for it deteriorates in a few days. 

Bacillus of Typhoid Fever. 1 — Synonyms: Bacillus 
typhi abdominalis ; Bacillus typhosus ; Typhoid bacillus. 

^berth: Virchow's Arch, f. Path. Anat., Bd. Si, 1SS0; Bd. 83, 1SS1 ; 
Gaffky : Mitth. a. d. Kais. Gesundheitsamte, Bd. 2, 1884. 



164 



PA THOL O GICAL TE CHNIQ UE. 



Blood-serum. — Round, grayish, viscid-looking colonies, 
which may attain a diameter of 2 mm. after forty-eight hours 
in the incubator. 



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Fig. 55 <— Diphtheria bacilli from blood-serum culture stained according to Hunt's 
method ; X 2000 (Wright and Brown). 

Morphology. — Medium-sized bacilli with rounded ends, 
generally short (Fig. 56), but sometimes long or thread-like, 



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FIG. 56. — Typhoid bacilli from a bouillon culture, showing characteristic irregu- 
larity in staining and variability in length ; X 2000 (Wright and Brown). 



and frequently showing faintly-stained, sharply-defined areas 
in their protoplasm (Figs. 56 and 57). 



BACTERIOLOGICAL METHODS. 1 65 

Gelatin Slant. — Broad translucent streak with wavy, 
irregular margins. The gelatin is not liquefied. Growth is 




FIG. 57.— Typhoid bacilli from a culture on potato, showing unstained areas in 
the bacilli and polar granules ; X 2000 (Wright and Brown). 

slower than that of the bacillus coli communis in the same 
medium. 

An isolated colony, slightly magnified, on gelatin, is shown 
in Fig. 58. 







■ : -:- : ". 

• tm -::■ . 



Fig. 58. — Bacillus of typhoid fever: superficial colony two days old, as seen 
upon the surface of a gelatin plate ; X 20 (Heim). 

Glncosc-gclatin Stab. — Growth all along the line of inocu- 
lation in the form of confluent spherical grayish colonies, and 
on the surface about the point of entrance of the platinum 



1 66 PATHOLOGICAL TECHNIQUE. 

wire in the form of a circular translucent grayish layer. No 
production of gas-bubbles. No liquefaction. 

Glucose Agar-agar. — Growth similar to that in the pre- 
ceding. No gas-formation. 

Litmus-milk. — No visible change. 

Potato. — Growth occurs, but it is usually invisible. 



FIG. 59- — Typhoid bacilli, from a culture on agar-agar, showing flagella, from a 
preparation stained by Dr. Hugh Williams; X 2000 (Wright and Brown). 

Dunham's Peptone Solution. — No indol-production — i. e. 
no red color appearing in the twenty-four- to forty-eight- 
hour cultures after the addition of 5 drops of concentrated 
sulphuric acid, c. p., and 1 cubic centimeter of a solution of 
sodium nitrite, 1 : 10,000. 

Motility. — Very marked. 



BACTERIOLOGICAL METHODS. 1 67 

Flagella (Fig. 59) may be demonstrated by the special 
methods of staining described elsewhere. 

Decolorized by Gram's method. Does not form spores. 

Bouillon. — Clouded, with the formation of some sediment. 
The clouding of the medium is not so marked as in the case 
of the bacillus coli communis. In general, the growth of the 
typhoid organism is not so vigorous on culture-media as is 
the growth of the bacillus coli communis. 

When to a bouillon culture a small quantity of the blood- 
serum of a typhoid-fever patient is added, the bacilli lose 
their motility and aggregate in clumps (" serum reaction "). 

Pathogenesis. — The inoculation of animals is usually with- 
out results if moderate quantities of the organism are used. 
Sometimes, however, death occurs apparently from the 
effects of the toxic material injected. 

Occurrence. — Found in the spleen in large numbers at 
autopsies in typhoid fever. Its presence may also be demon- 
strated in the intestinal lesions, rose spots, mesenteric lymph- 
glands, liver, bile, kidneys, urine, and blood of the heart. 
As a rule, the number of bacilli found in the liver, kidneys, 
and blood of the heart is small. In the bile they may be 
numerous and may persist in it for a long period of time 
after the disease has subsided. In some cases the urine con- 
tains enormous numbers of the bacilli. 

The typhoid bacillus may also occur in the suppurative 
sequelae of typhoid fever, especially those involving bones. 
In these conditions, however, it may be accompanied by the 
pyogenic cocci. Occurs in contaminated water. 

Differential Diagnosis between the Bacillus of Typhoid 
Fever and the Bacillus Coli Communis. — The most im- 
portant points of difference between these two organisms are 
as follows, and to distinguish with certainty between them it 
is necessary that attention be paid to all of them : 

Motility. — The typhoid bacillus is actively motile, the 
bacillus coli communis not motile or exceptionally motile. 

Potato Cultures. — The typhoid bacillus usually grows in- 
visibly, the bacillus coli communis as a dirty, slimy layer. 



1 68 PATHOLOGICAL TECHNIQUE. 

Gas-production in Media Containing Glucose. — The bacillus 
coli communis produces gas, the typhoid bacillus does not. 

Litmus-milk Cultures. — The bacillus coli communis changes 
the blue color of the medium to a pink color and usually 
coagulates the milk. The typhoid bacillus produces no 
visible change. 

Indol-production. — The bacillus coli communis produces 
indol, the typhoid bacillus does not. 

Serum or Clump Reaction. — The typhoid bacillus shows 
the clump reaction, while the bacillus coli communis does 
not. As it is not always possible to have a typhoid serum 
at hand by which to determine whether this reaction is 
present, a stock of dried blood from a typhoid case, con- 
tained in filter-paper, may be kept ready for use. That this 
is quite practicable has been clearly shown by Dr. Mark W. 
Richardson. The blood may be obtained from the heart at 
the autopsy of a typhoid-fever case by soaking a piece of 
filter-paper with it. This is allowed to dry, and then is cut 
into pieces about I cm. square. When it is desired to make 
the test, one of these pieces is extracted with ten or fifteen 
drops of water, and a drop of this extract is mixed with a 
drop of an eighteen- to twenty-four-hour bouillon culture 
on a slide, covered with a cover-glass, and examined with 
the high-power dry lens. Dr. Richardson has found that 
the blood under these conditions retains for months its 
" clumping " power with reference to the typhoid bacillus. 

Other differences are — the production of a red color in 
litmus-lactose agar-agar by the bacillus coli communis, and 
no change in color of this medium by the typhoid bacillus, 
and the slower and less vigorous growth of the typhoid 
bacillus in culture-media. 

The Blood-serum Reaction in Typhoid Fever. — A few 
drops of the blood of a suspected case of typhoid fever are 
collected in a small test-tube, either from the finger or the 
ear. After clotting has taken place, transfer a drop of the 
serum by means of a medicine-dropper to forty drops of 
a recent bouillon culture of the typhoid bacillus. After 
mixing, place a drop of the mixture on a slide, cover it 



BACTERIOLOGICAL METHODS. 169 

with a cover-glass, and examine with a high-power dry 
objective. 

If the bacilli are seen to be motionless and to be agglom- 
erated in clumps within twenty minutes, the reaction is to be 
regarded as present and typical. If the clumping occurs 
within thirty minutes, but free bacilli are still moving, the 
reaction is to be regarded as doubtful. The reaction is 
present, as a rule, only after the first week of typhoid fever. 
The slide and cover-glass should be sterilized in a flame 



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FlG. 60. — Showing the clumping of typhoid bacilli in the serum-reaction. 
Wet preparation, not stained. At one point a crenated red blood-corpuscle is 
seen (Wright and Brown). 

after the test is completed. The bouillon culture used 
should be grown at room-temperature and should not be 
more than four or five days old. Before carrying out the 
test it is well to assure one's self that the bacteria are 
actively motile by examining a drop of the culture as above 
indicated. The stock cultures of the typhoid bacilli are 
best made on agar-agar. 

The reaction may also be obtained from the dried blood. 
A few drops of the blood may be collected on a glass slide 
or a piece of paper and allowed to dry. It may then be 
brought to the laboratory, where as much of the dried blood 
as would correspond to a drop is scraped from the slide into 
a small test-tube, containing forty drops of a bouillon-culture 
of the typhoid bacillus, or as much of the paper as may be 



170 PATHOLOGICAL TECHNIQUE. 

assumed to contain one drop of blood is placed in forty drops 
of the bouillon culture and allowed to soak for a few minutes 
therein. Microscopical examination is then made with the 
mixture thus obtained as above indicated. 

Cultivation of the Typhoid Bacillus from the Blood 
during" Life. — The method of doing this is indicated on 
page 98. It is important that at least 10 c.c. of the blood 
should be obtained and that this be mixed with a large 
excess of sterile bouillon — say 1 or 2 c.c. to 200 or 400 c.c. 
of bouillon in flasks. 

Cultivation of the Typhoid Bacillus from Rose Spots. — - 
Dr. Mark W. Richardson, of Boston, uses the following 
method : The skin is first washed with corrosive sublimate 
and then with alcohol and ether. The skin about the spot 
is then frozen with ethyl chlorid and a small crucial incision 
made in it. The wound is immediately scraped with a very 
small curette, and with the material so obtained a bouillon 
tube is inoculated. It is not to be expected that the bacillus 
will develop in every culture so made. 

Cultivation of the Typhoid Bacillus from the Feces. 
— Various culture-media have been devised upon which 
colonies of typhoid bacilli will grow with appearances dis- 
tinguishing them from colonies of colon bacilli and other 
bacteria. Of these, we here describe but two. In all cases 
the colonies supposed to be those of the typhoid bacillus 
should be proved by transplants in various media and the 
bacteria shown to conform to the requirements indicated on 
pages 167 and 168. 

Medium of Hiss} — This is composed of agar-agar 1 5 gm. ; 
gelatin, 15 gm. ; Liebig's extract of meat, 5 gm. ; sodium 
chlorid, 5 gm. ; dextrose, 10 gm. ; distilled water, 1000 c.c. 

The agar-agar is dissolved in water by boiling for thirty to 
forty-five minutes. The other ingredients, except the dex- 
trose, are then added. When dissolved, the mixture is 
cleared with the whites of two eggs and filtered through 
absorbent cotton. The sugar is added to the filtered mix- 
ture. The medium thus prepared is then run into tubes — 

1 Journal of Medical Research, June, 1902, vol. viii., No. I, pp. 148-167. 



BACTERIOLOGICAL METHODS. 171 

10 c.c. in each tube — and sterilized at ioo° C. in the usual 
manner on three successive days. 

Make an emulsion of one or more loopsful of the feces in 
sterile bouillon and from this make five or six plate-cultures 
with the medium, using one to five loopsful of the emulsion 
to each plate. The plates are to be examined after twelve to 
eighteen hours in the incubator. 

The colonies of typhoid bacilli below the surface of the 
medium are of irregular shape and present filamentous or 
thread-like processes extending into the medium. The colo- 
nies of colon bacilli beneath the surface of the medium are 
larger, denser, and darker, and do not present the filament- 
ous processes. The surface colonies of the typhoid bacillus 
are smaller, less dense, thinner, and more homogeneous than 
are the colonies of colon bacilli. 

Medium of v. Drigalski and Conradi} — (a) Preparation of 
agar : 1 kilo of finely ground beef is mixed with two liters 
of water and allowed to stand until the next day. The re- 
sulting meat infusion is boiled for an hour, filtered, and to it 
are added 20 gm. of peptone (Witte), 20 gm. neutrose, 10 gm. 
sodium chlorid, and the whole boiled for another hour and 
filtered. To the filtrate 60 gm. of agar-agar are added and 
the mixture boiled for three hours (or one hour in the auto- 
clave), is made faintly alkaline to litmus, is again filtered, and 
is boiled one-half hour more. 

(b) Litmus solution : litmus solution (according to Kubel 
and Tiemann), 260 c.c, boil ten minutes, add 30 gm. chemi- 
cally pure lactose, and boil for fifteen minutes. 

(c) Add the hot litmus-lactose solution to the fluid agar. 
Shake well and readjust, if necessary, to a weak alkaline 
reaction. Next add 4 c.c. of a hot sterile solution of 10 per 
cent, anhydrous sodium carbonate and 20 c.c. of a freshly 
prepared solution of 0.1 gm. of crystal violet (B. Hochst) in 
100 c.c. of warm sterile distilled water. 

This medium should be stored in flasks of about 200 c.c. 
capacity in order to avoid protracted heating when it is de- 
sired to melt it. When used, the medium is poured into 

1 Zeitschrift fur Hygiene und Infectionskrankheiten, 1902, Bd. 39. p. 2S3. 



172 PATHOLOGICAL TECHNIQUE. 

round glass plates 15 to 20 cm. in diameter in sufficient 
amount to form a layer at least 2 mm. thick and is allowed 
to solidify. Its surface is then inoculated with a suspen- 
sion of the fecal material, applied by means of a glass rod 
bent in a certain form. Obvious means are to be taken 
to secure such a distribution of the bacteria that a good 
separation of the colonies will result. After inoculation the 
medium is to remain uncovered in the plates until the sur- 
face is dry. 

After twenty-four hours in the incubator the colonies of 
the typhoid bacillus are blue in color and smaller than the 
colonies of colon bacilli, which are red and opaque. Colo- 
nies of other bacteria may be blue, but they are generally 
larger. 

Bacillus Coli Communis. 1 — Synonyms : Bacterium coli 
commune ; Colon bacillus. 









% 






*V" 


■:*£/;* 3} s 






f s 


,/ /■ 


9 *v 


s C 




mm V 


3/ 


* 
< 


*/ 


N . V* 


#"" 





Fig. 61. — Bacilli coli communis from a bouillon culture, showing the irregu- 
larity of staining of the bacillus ; X 200 ° (Wright and Brown). 

Blood-serum. — Rounded, grayish-white, slightly elevated, 
viscid-looking colonies, which may attain a diameter of 3 mm. 
after twenty-four hours in the incubator. 

Morphology. — A medium-sized bacillus with rounded ends, 
1 Escherich : Fortschr. d. Medicin, 1885, Nos. 16, 17. 



BACTERIOLOGICAL METHODS. I 73 

often short or even coccus-like, but may grow in long forms. 
Faintly staining, sharply defined areas are present in the pro- 
toplasm (Fig. 61). 

Gelatin Slant. — Grayish translucent strip with wavy mar- 
gins. The gelatin is not liquefied. Growth is more rapid 
than in the case of the typhoid bacillus. 

A single colony on a gelatin plate is shown in Fig. 62. 

Glucose-gelatin Stab. — Growth along the line of stab in 
the form of confluent spherical colonies, and on the surface 
about the point of entrance of the needle as a thin gray 




Fig. 62. — Bacillus coli communis : superficial colony two days old upon a 
gelatin plate ; X 21 (Heim). 

circular layer. Gas-bubbles are produced in the gelatin 
from fermentation of the glucose. The gelatin is not 
liquefied. 

Glucose-agar-agar Stab. — Growth essentially the same as 
in the preceding, except that the gas-formation is more 
marked. 

Litmus-milk. — Turned pink and usually coagulated. 

Potato. — Dirty grayish or brownish, viscid-looking layer. 

Dunham's Peptone Solution. — Marked indol-production. 
This is shown by the appearance of a red color in the cul- 
ture after the addition of 5 drops of concentrated sulphuric 
acid, c. p., and 1 c.c. of a 1 : 10,000 solution of sodium 
nitrite. The culture in the peptone solution should have 



174 PATHOLOGICAL TECHNIQUE. 

been at least twenty-four hours — or, better, forty-eight hours 
— in the incubator before the test is made. 

Motility. — Usually not motile, but some varieties show 
sluggish independent movement. 

Flagella. — May be demonstrated by the special methods 
of staining. They are less numerous than in the case of the 
typhoid bacillus. 

Decolorized by Gram's method. 

Bouillon. — Markedly clouded, with formation of a sedi- 
ment. The clouding is more marked than in the case of 
the typhoid bacillus. 

Lactose-litmus-agar-agar Slant. — Growth has a pink color, 
and the blue color of the medium is changed to red. 

Pathogenesis. — " Its virulence as tested upon animals is 
variable, but is generally manifest only after inoculation of 
large doses, which kill by intoxication rather than infection " 
(Welch). 

The lesions produced are not sufficiently characteristic to 
be detailed here. 

Occurrence. — Occurs constantly in the intestinal canal, and 
is widely distributed in the external world. 

" The colon bacillus is a frequent invader of the internal 
organs in all sorts of diseases, especially when there are in- 
testinal lesions. It manifests no evident pathogenic action 
in most of these cases, and is then without clinical signifi- 
cance. It occurs frequently associated with other bacteria 
in infected wounds and other inflammations of exposed sur- 
faces. Here also it does not usually appear to cause serious 
disturbance. The fact that the colon bacillus is so common 
and widely distributed, and found so often as a harmless in- 
vader, should lead to much caution in interpreting the sig- 
nificance of its presence when it occurs in definite lesions. 
There is no doubt, however, that it may be pathogenic for 
man. It plays an important role in inflammations of the 
urinary tract and biliary passages ; also, but usually with 
less independence, in peritonitis and appendicitis. 

" The list of diseases in which it may be found is a very 
long one, and includes inflammations in all organs and parts 



BACTERIOLOGICAL METHODS. 1 75 

of the body. In general its pathogenic properties are of a 
mild character. One of its leading roles is to invade terri- 
tory already occupied by other bacteria or previously 
damaged. It may be concerned in the production of gall- 
stones, in the interior of which it has been found by the 
writer with great frequency " (Welch, Dennis's System of 
Surgery \ vol. i.). 

The bacillus above described is to be regarded as a type of a 
group of bacilli constituting the so-called "colon group" of 
bacilli. These present certain quantitative differences among 
themselves which are not quite sufficient to characterize them as 
distinct species. 

Welch regards as belonging to this group the Bacillus pyogenes 
foetidus, distinguished by the stinking odor of its cultures, and 
the Bacillus lactis aerogenes, which is characterized chiefly by its 
plumper form, its more energetic gas-production, its rapid coagu- 
lation in milk, and its denser growth in cultures. 

Theobald Smith 1 suggests that only those forms may be re- 
garded as typical members of the group which grow on gelatin 
in the form of delicate bluish or more opaque whitish expansions 
with irregular margin, which are actively motile when examined 
in the hanging-drop from young surface colonies taken from gela- 
tin plates, which coagulate milk within a few days ; grow upon 
potato either as a rich pale or brownish-yellow deposit, or merely 
as a glistening, barely recognizable layer, and which give a dis- 
tinct indol-reaction. Their behavior in the fermentation-tube 2 
must conform to the following scheme : 

1 Amer. Jour. Med. Sci., Sept., 1 895. 

2 The fermentation- tube is a special form of culture-tube which may be 
obtained from dealers in bacteriological supplies. The closed branch of the 
tube should be completely filled with culture-fluid, but no more fluid should 
be placed in the tube than can be conveniently held by the open branch of the 
tube, so that if gas be formed in the closed branch the culture-fluid will not be 
forced out of the apparatus. The bubbles which collect at the top of the closed 
branch, after heating during sterilization, should be removed by an appropriate 
tilting of the tube. Theobald Smith,* who was the first to demonstrate the 
great value of the fermentation-tube in bacteriology, thus describes the mode 
of its use : 

" The tubes are kept, after inoculation, in the thermostat at 37 C. A mark 
made on the sides of the closed branch at the end of every twenty-four hours 
with a glass pencil furnishes an approximate record of die rate of gas-produc- 
tion. Unless this is done it is impossible to know precisely when the formation 
of gas is at an end, and also whether or not the volume of gas has been dimin- 
ished by absorption. It is best to wait four or five days after the production 
* The Wilder Quarter- Century Book, Ithaca, 1S93, pp. 1S6, 187. 



176 PATHOLOGICAL TECHNIQUE. 

Variety a. One per cent, dextrose-bouillon (at 37 C). 

Total gas, approximately 1/2 ; H/C0 2 approximately 2/1 ; 

reaction strongly acid. 
One per cent, lactose bouillon : 
As in dextrose-bouillon (with slight variation). 
One per cent, saccharose-bouillon : 

Gas-production slower than in the preceding, lasting from 
seven to fourteen days. Total gas finally about 2/3 ; 
H/C0 2 nearly 3/2. The final reaction in the bulb may 
be slightly acid or alkaline, according to the rate of gas- 
production. 
Variety /?. The same in all respects excepting as to its behavior in 
saccharose-bouillon. Neither gas nor acids are formed in it. 
The Detection of the Bacillus Coli Communis in Water. 
— The presence of bacilli of the " colon group " in water is to be 

has ceased before making a final examination. This is done by noting the 
condition of the growth, the reaction of the fluid in the bulb,* and the maxi- 
mum quantity of gas produced. This is most easily done by laying directly 
on the tube a glass millimeter rule, and noting the tube length occupied by gas. 
The entire length of the closed branch is also noted, making due allowance for 
the upper convex extremity and the lower constriction. This mode of meas- 
urement is sufficient, since only comparative values are desired. For the same 
reason all barometric and thermometric corrections are omitted in these approxi- 
mate estimations. 

" The examination of the gas produced was limited to the determination of 
the quantity of carbon dioxid and of the explosive character of the gas remain- 
ing after the absorption of C0 2 by sodium hydrate. These facts are deter- 
mined by the following simple manipulations : 

" The bulb is completely filled with a 2 per cent, solution of NaHO, and 
closed tightly with the thumb. The fluid is shaken thoroughly with the gas, 
and allowed to flow back and forth from bulb to closed branch and the reverse 
several times, to insure intimate contact of the C0 2 with the alkali. Lastly, 
before removing the thumb, all the gas is allowed to collect in the closed branch 
so that none may escape when the thumb is removed. If C0 2 was present, a 
partial vacuum in the closed branch causes the fluid to rise suddenly when the 
thumb is removed. After allowing the layer of foam to subside somewhat, 
the glass scale is again applied to the closed branch, and the amount of C0 2 
absorbed may thus be measured. In all cultures of this character thus far ex- 
amined the gas remaining was explosive in character, and probably hydrogen. 
The explosive character of this residue is easily demonstrated as follows : The 
cotton plug is replaced, and the gas in the closed branch allowed to flow into 
the bulb, and mix with the air there present. The plug is then removed, and 
a lighted match inserted into the mouth of the bulb. The intensity of the 
explosion varies with the quantity of air present in the bulb." 

* The reaction was noted by placing a drop of the fluid on delicate litmus- 
paper. The cultures were occasionally boiled to drive off any C0 2 . In no 
case did the reaction with the litmus-paper change. 



BACTERIOLOGICAL METHODS. 1 77 

regarded as good evidence of pollution with fecal material from 
man or animals. 

Theobald Smith's Method. 1 — A certain quantity of the water 
is added "to every one of ten fermentation -tubes containing a 
1 per cent, dextrose-bouillon. This is added most easily by first 
diluting the water, so that 1 or 2 c.cm. are equivalent to the 
quantity which it is desired to add to each tube. Pipettes gradu- 
ated by drops are convenient, but not so accurate." "When 
gas begins to appear in the fermentation-tubes the amount accu- 
mulated at the end of each twenty-four hours should be marked 
with a glass pencil on the tube. From these tubes, which con- 
tain 50 to 60 per cent, of gas on the third day, and are very 
strongly acid, plates may be prepared to confirm the indications 
of B. colt. This, however, is not essential, for the writer has 
found as yet no species having these fermentative characters 
which is not one of the following: B. coli, B. lactis aerogenes, 
B. enteritidis, B. typhi tnurium, B. cholera suis. The three last- 
mentioned species are probably as rare in water as B. typhosus 
itself." 

Paratyphoid and Paracolon Bacilli. — Under these 
names certain observers have grouped various bacilli that 
they have found associated with inflammatory processes and 
with fevers clinically resembling typhoid. These bacilli have 
certain cultural peculiarities, like the typhoid bacillus and 
the colon bacillus, but they differ from them and from each 
other in certain cultural peculiarities which chiefly concern 
their fermentation of the various sugars, their effect upon 
litmus milk, their mode of growth on potato, and their indol 
production. At the present time it seems impossible to give 
a detailed description of the behavior of any one of them 
on the various culture-media that will hold good for another. 
They are not agglutinated by typhoid serum, but each qf 
them is agglutinated by the serum of the patient from which 
it is derived. 

Bacillus Dysenteriae (Shiga). — This bacillus resembles 
the typhoid bacillus in morphology, but in general it is 
plumper and less frequently appears in filamentous forms. 
Involution forms quickly develop in glucose-agar cultures. 
It is decolorized by Gram's method, and does not form 
spores. It is not motile. The bacillus grows in bouillon 
and on agar and gelatin, both in plate and tube cultures, 

1 Amer. Jour. Med. Sci., Sept., 1895. 
12 



1/8 PATHOLOGICAL TECHNIQUE, 

with appearances very similar to those of the typhoid 
bacillus. It does not produce gas in media containing 
glucose or other sugars. 

Typical examples of the bacillus do not produce indol 
in peptone solution, but some strains have been found to 
do so. 

Litmus Milk. — During the first two or three days the milk 
becomes a pink color, but later becomes blue. It is never 
coagulated. 

Potato. — Growth, at first in the form of a moist, colorless, 
slimy, almost invisible layer, becoming, after two or three 
days in the incubator, of a yellowish to brownish tint with 
discoloration of the potato. 

Mannite Litmus Agar. — This medium consists of ordinary 
nutrient agar-agar containing I per cent, of mannite and I 
per cent, of a 5 per cent, aqueous solution of litmus. The 
agar-agar should have been made up with meat infusion 
free from muscle-sugar (see p. 74). In stab cultures on 
this medium the typical bacillus decolorizes the agar in the 
depths, but near the surface the original blue color remains 
unchanged. Some strains of the bacillus, however, change 
the color of the upper layers to red, as do typhoid and colon 
bacilli. Thus two varieties of the bacillus may be distin- 
guished with reference to their effect on this culture-medium. 
Both of these varieties have been isolated from the same 
dysenteric stools. 

The bacillus exhibits the agglutination reaction with the 
serum of dysenteric cases and with the serum of animals 
immunized against the bacillus. 

Pathogenesis. — The bacillus is pathogenic for the usual 
laboratory animals, especially for mice and guinea-pigs^ 
which may die in from twenty-four to forty-eight hours after 
subcutaneous or intraperitoneal inoculation. At the autopsy 
there may be found local inflammation at the seat of inocu- 
lation, ecchymoses of the serous membranes, serous or sero- 
hemorrhagic exudate in the pleural or peritoneal cavities, 
enlargement of the spleen, and hyperemia or hemorrhage in 
the intestinal walls. 



BACTERIOLOGICAL METHODS. 1 79 

Occurrence. — In the stools, intestinal contents, and in the 
ulcerated mucous membrane of acute dysentery, whether 
sporadic or epidemic. It may be found in the mesenteric 
lymphatic glands, but is not found in the blood, in the 
spleen, or in other viscera. 

Method of Isolation of the Bacillus. — A small portion 
of mucus is to be broken up in a tube of sterile bouillon. 
From the suspension of bacilli thus obtained agar-agar 
plate-cultures are prepared in dilutions depending upon the 
number of bacilli observed in smear preparations of the 
mucus. After twenty-four hours in the incubator trans- 
plants are made from colonies resembling those of the typhoid 
bacillus into 1 per cent, glucose bouillon contained in tubes 
arranged as suggested by Durham for the demonstration of 
gas-formation. These tubes are prepared as follows : 

In an ordinary bacteriological test-tube containing about 
one-third more than usual of 1 per cent, glucose bouillon, 
there is placed a small test-tube mouth downward. The 
larger tube is then plugged with cotton, and is sterilized by 
steam in the usual way. After the sterilization it will be 
found that the air has been driven out of the inverted inner 
tube and has been replaced by the bouillon. When cool, 
the tube is ready for inoculation. If the bouillon at the 
bottom of the larger tube be inoculated with a bacterium 
capable of fermenting glucose with the production of gas, 
this property of the bacterium will manifest itself by the 
collection of gas in the upper part of the small inverted 
inner tube. 

As the dysentery bacillus does not produce gas from 
glucose, gas-formation in a tube is proof that the colony 
from which it was inoculated is not the dysentery bacillus. 
The bacteria in tubes in which no gas has developed are to 
be examined with reference to morphology and motility. 
If found to agree in morphology with the bacillus of dysen- 
tery and to be non-motile, then the agglutination test with 
dysentery serum may be applied to them immediately and 
they are to be transplanted on the various media to test 
their cultural peculiarities. 



i8o 



PA THOL O GICAL TECHNIQ UE. 



The advantages of this method over that of first trans- 
planting the suspected colony into sugar-agar, as is usually 
done, are, first, that it enables the motility, agglutination re- 
action of the bacilli, and any gas-formation to be determined 
with the use of a single culture-tube ; and, second, that it 
dispenses with the use of glucose-agar tubes, which are 
much more troublesome to prepare than are the bouillon 
tubes. These considerations are of considerable importance 
when a number of cases are being examined, for at least six 
colonies should be tested in each case as above described. 

Bacillus Tuberculosis. 1 — Synonyms: Tubercle bacillus ; 
Bacillus of Koch. 

Blood-serum. — After three or four weeks in the incubator 
the colonies appear as dry, cream- colored, granular, slightly 




Fig. 63. — Branched tubercle bacilli from sputum ; X 20O ° (Wright and Brown). 

elevated patches with irregular margins, 1 to 2 mm. in diam- 
eter. They may become confluent, to form a dense, dry, 
granular mass with irregular surface and of a creamy-white 
color. The growth is very friable, but coherent, and may 
be picked up in clumps on the platinum wire. The first 
generation from tissues is very slow in developing, but suc- 
ceeding generations grow more rapidly, and may form a 
wrinkled, dry, cream-colored membranous layer on the sur- 
face of the medium. 

Morphology. — Slender rods, usually shorter than when 
observed in sputum, and in fresh cultures staining homo- 
geneously ; in older cultures presenting a segmented or 

1 Koch : Berlin, klin. Wochenschr., No. 15, 1882 ; Mitth. a. d. Kais. Ge- 
sundheitsamte, Bd. 2, 1 884. 



BACTERIOLOGICAL METHODS. l8l 

irregularly stained appearance. They frequently occur in 
pairs of short rods and in closely adhering clumps and 
strands. When once stained with fuchsin or gentian-violet 
they are not decolorized by treatment with Gabbet's solution 
or with a 20 per cent, solution of any of the mineral acids, 
followed by alcohol. In the sputum of pulmonary tuber- 
culosis the bacillus sometimes occurs in filaments which 
branch. On this account the organism is considered by 
many to belong to the group of the streptothrices (see 
P- 227). 

Stained by Gram's method. Not motile. Does not form 
spores. 

Glycerin Agar-agar Slant. — Growth similar to that on 
blood-serum, but not so vigorous. By continued inoculation 
of this medium through a number of generations, however, 
the organism may eventually grow luxuriantly upon it. 

Glycerin Bouillon. — Growth on the surface in the form of 
floating patches or as a membrane similar in appearance 
to the growth on blood-serum. The growth sinks to the 
bottom from time to time. The glycerin-bouillon culture is 
best contained in Erlenmeyer flasks, filled to such a depth 
as to give a wide surface to the fluid and thus permit the 
access of plenty of oxygen to the growth. 

Potato. — The growth is not remarkable. 

Agar-agar or bouillon not containing glycerin is not suit- 
able for the cultivation of this bacillus. 

Pathogenesis. — The inoculation of guinea-pigs or rabbits 
by any method is followed by the development of general 
miliary tuberculosis. Guinea-pigs are most susceptible. 
These animals usually survive about two or three months, 
with marked emaciation. The lesions in the spleen and liver 
in the guinea-pig are characterized by extensive areas of 
necrosis not confined to the tubercular tissue, large parts 
of these organs being transformed into a firm yellow, opaque, 
friable material. 

Isolation of the Bacillus Tuberculosis from Tubercular 
Lesions. — The tubercular lesions in human tissues are not 
ordinarily favorable for the isolation of the bacillus, on 



1 82 PATHOLOGICAL TECHNIQUE. 

account of the frequent presence of other bacteria in them 
and because of the small number of tubercle bacilli usually 
present in tissue otherwise suitable. The best method of 
procedure is to inoculate a guinea-pig subcutaneously in the 
abdominal wall with tubercular material, and after four to 
six weeks, when the inguinal lymphatic glands have become 
enlarged, to kill the animal and make cultures on suitable 
media from tuberculous lymphatic glands. The object of 
killing the animal, rather than allowing it to die sponta- 
neously, is to secure fresh tissue and to avoid the chance 
of an invasion of the lesions by other bacteria. 

For the cultivation of tubercle bacilli from tubercular 
lesions, M. Dorset highly recommends his egg-medium, 
which is prepared as follows : 

Fresh eggs are broken under aseptic precautions into a 
wide-mouthed sterile flask, and the white and yolk mixed 
thoroughly. - To every four eggs add 25 c.c. of sterile water. 
Any foam may be removed by straining the mixture through 
a sterile cloth. The mixture is then run into sterile tubes, — 
about 10 c.c. into each tube, — and slowly hardened in the 
form of " slants " in a blood-serum oven at a temperature 
of 73 to 76 C. This degree of temperature should be 
maintained for four or five hours on three successive days. 
On the first two days the temperature is maintained at 73 
C, and on the third day alt 76 C. Just before inoculating 
the medium three or four drops of sterile distilled water 
should be added to each tube to supply the moisture 
required for the satisfactory development of the tubercle 
bacillus. 

After inoculation the tube should be placed in the incu- 
bator at 38 C. in an inclined position, so that the surface of 
the medium may keep moist. Colonies first become visi- 
ble after seven or eight days in the incubator. 

A number of tubes are to be inoculated, say three or four, 
from each of the two or three glands, a large quantity of 
material being spread upon the surface of each tube. Great 
care is to be exercised to avoid contamination with other 
bacteria in preparing these cultures. The culture-tubes used 



BACTERIOLOGICAL METHODS. 1 83 

should contain freshly prepared moist medium, and imme- 
diately after inoculation should be sealed air-tight to prevent 
evaporation. This may conveniently be done by first cutting 
off the projecting portion of the cotton stopper and insert- 
ing a cork into the mouth of the tube in such a way as to 
push the cotton stopper before it. 

In order to prevent the invasion of fungi from the cotton, 
the neck of the tube should be heated in the Bunsen flame 
until the cotton begins to brown before inserting the cork, 
which should also be charred in the Bunsen flame before in- 
sertion. The tubes may also be sealed with wax or paraffin 
or covered with small rubber caps. 

Wolbach and Ernst x have noted the following chief points 
of difference between tubercle bacilli from human and from 
bovine lesions when cultivated on Dorset's egg medium. 
The human cultures as compared with the bovine cultures 
grow more profusely and the membranous layer that is 
formed is more nodular, drier looking, less translucent, more 
adherent to the medium, harder, and more difficult to break 
up with the platinum wire. The human bacilli generally 
show a slightly greater variation in length and thickness 
than do the bovine bacilli. 

Occurrence. — In tubercular lesions generally and in the 
sputum of pulmonary phthisis, in the urine in many cases 
of genito-urinary tuberculosis, and in the feces in intestinal 
tuberculosis. The tuberculosis of cattle and of birds is due 
to different varieties of this bacillus. 

Does not multiply outside of the body except in cultures. 

May occur on the surface of objects contaminated with 
the excreta of tuberculous individuals or in the dust of places 
inhabited by such individuals. 

Diagnosis. — For clinical purposes the tubercle bacillus 
may be identified in cover-glass preparations by means of 
the special methods of staining, which depend upon the fact 
that the bacillus tuberculosis, when once thoroughly stained 
with an aniline dye, does not give up its stain in the presence 
of acids, as nearly all other bacteria do. The bacillus tuber- 

1 Journal of Medical Research, December, 1903, vol. x., No. 3, p, 313. 



1 84 PATHOLOGICAL TECHNIQUE. 

culosis may therefore be identified even among a mixture of 
other bacteria by this property, taken in connection with its 
morphology, in most of the routine work of the pathological 
laboratory. Practically, the only other bacilli with which it 
may be confounded are the bacillus of leprosy and the 
smegma bacillus, both of which, when stained, resist the 
decolorizing action of acid. It may be differentiated from 
the smegma bacillus by the fact that it is not decolorized by 
alcohol (95 per cent.) after the usual treatment with acid, 
while the smegma bacillus is decolorized under these circum- 
stances. 

As a rule, the differential test with alcohol need only be 
applied in the examination of urine and the material derived 
from about the external genitalia, especially in the case of 
females. 

The differentiation from the bacillus of leprosy by certain 
quantitative differences in staining reactions has been at- 
tempted, but it is very unsatisfactory, and it is doubtful if 
there is as yet any reliable method of distinguishing between 
these two organisms, considered by themselves. 

Examination of Sputum for Tubercle Bacilli. — 
The morning sputum should be taken for examination. 
Select one of the dense, grayish- white particles, and Avith 
the aid of small pointed forceps or the platinum wire rub it 
over the surface of a cover-glass, breaking it up as much as 
possible. The material should be spread in a very thin layer. 
The preparation is next to be " fixed " in the ordinary way 
described for cover-glass preparations (see p. 92), and is 
thee to be treated as follows * 

1. Stain in carbol-fuchsin solution, steaming for one minute 
over the Bunsen flame, with the staining solution thoroughly 
covering all the surface of the cover-glass. None of the 
surface of the cover-glass should be allowed to become dry 
by evaporation, as this causes a precipitate to form, but more 
of the staining fluid should be added from time to time to 
keep it completely covered as evaporation occurs. The 
object of the heating is thoroughly to impregnate the bacilli 
with the dye. 



BACTERIOLOGICAL METHODS. 1 85 

2. Wash in water. 

3. Decolorize in a 30 per cent, aqueous solution of con- 
centrated nitric acid until the red color disappears. Do not 
allow the acid to act on the preparation longer than a few 
seconds. The solution should also be applied to the un- 






' -N ( / 



Fig. 64. — Tubercle bacilli in sputum (carbol-fuchsin and methylene-blue). 

charged side of the cover-glass to remove any dried stain 
which may have collected thereon. 

4. Wash thoroughly in water. 

5. Wash in 95 per cent, alcohol for thirty seconds. 

6. Wash in water and mount. 

The tubercle bacilli are stained red and the nuclei of cells 
and other bacteria are stained blue. 

Tubercle bacilli, when present in sputum in very small numbers, 
may sometimes be demonstrated by methods of sedimentation. A 
good means of sedimentation consists in heating the sputum in a 
test-tube either with boiling water or in the steam sterilizer for 
fifteen minutes. The heat coagulates the cells and albuminous 
constituents, which sink to the bottom, carrying with them the 



1 86 PATHOLOGICAL TECHNIQUE. 

bacilli. The supernatant liquid may then be poured off and the 
sediment examined as above. 

Another method of treating the sputum when only a small 
number of bacilli may be present is as follows: Place 10-15 cc - 
of the sputum in a wide-mouthed bottle of 100 c.c. capacity. 
Add 10 c.c. of water and 6 c.c. of liquefied carbolic-acid crystals. 
Close the flask with a rubber cork and shake for one minute. 
After shaking, fill the bottle with water and shake again. Then 
pour the contents of the bottle into a sedimenting glass, let stand 
for twelve to twenty-four hours, and examine the sediment. The 
cover-glass preparations of the sediment before staining are to be 
washed in ether or chloroform, and then in alcohol, or they may 
be washed in a mixture of alcohol and ether, equal parts. 

In a very few cases of gangrene of the lung bacilli like smegma 
bacilli have been found in the sputum. These may be mistaken 
for tubercle bacilli {vide ante). 

Tubercle Bacilli in Urine. — The sediment of the urine 
should be examined. This may be rapidly thrown down by 
the centrifuge. With the sediment, cover-glass preparations 
are to be made and stained as described for sputum. Especial 
care should be taken to wash thoroughly in alcohol after the 
decolorization with acid, in order to decolorize any smegma 
bacilli that may be present. (See remarks on Diagnosis, 
p. 183.) Because smegma bacilli may be mistaken for 
tubercle bacilli and because the tubercle bacilli may be so 
few as to escape observation, the inoculation of a guinea-pig 
with the sediment is the better test for the presence of tuber- 
cle bacilli in the urine. For this purpose the urine should 
be collected in sterilized vessels and immediately centrifu- 
galized in sterilized tubes. The sediment is then to be 
injected subcutaneously into a guinea-pig with a sterilized 
syringe. (See p. 1 16.) 

Surgical Tuberculosis. — The demonstration of the 
tuberculous nature of material removed at operations may 
be made by the histological examination, by the demonstra- 
tion of the tubercle bacilli on cover-glass preparations, as in 
sputum, and by the results of the inoculation of guinea-pigs 
with the material. Cultures are not ordinarily practicable. 

The examination of cover-glass preparations is commonly 
of little value, owing to the small number of bacilli usually 
present. 



BACTERIOLOGICAL METHODS. 1 87 

The histological examination may be often made very satis- 
factorily by the method of frozen sections described on 
p. 263. 

The inoculation of guinea-pigs is to be made subcutane- 
ously in the abdominal wall, either with a hypodermic syr- 
inge if the material is fluid, or, if it be in the form of tissue, by 
inserting a small piece beneath the skin. Material obtained 
on a swab may also be used for inoculation by introducing 



*£*'■*•' w ■;>/. 





^lm%^ ft* 



FIG. 65. — Bacillus of leprosy : section through a cutaneous nodule, showing the 
bacilli in the tissue ; X 750 (Wright and Brown). 

the infected swab beneath the skin and moving it back and 
forth a few times. If tubercle bacilli are present in the ma- 
terial, the animal will show enlargement of the inguinal 
lymphatic glands in about three weeks and will usually die 
of miliary tuberculosis in the course of six to ten weeks. If 
necessary, the glands in the inguinal region may be examined 
histologically after three weeks for the presence of tubercu- 
lar lesions, or examined by cover-glass preparations for tu- 



1 88 PATHOLOGICAL TECHNIQUE. 

bercle bacilli. The discharges from sinuses, etc. may also 
be tested for the presence of tubercle bacilli as above indi- 
cated, the material being obtained on a " swab." 

lyeprosy. — The bacillus of this" disease shows essentially 
the same staining reactions as the bacillus tuberculosis. In 
sections of the lesions the bacilli are found in large numbers, 
mostly inside the tissue-cells (see Fig. 65). 

Spirillum of Asiatic Cholera (Comma Bacillus). 1 — 
Morphology (Figs. 66, 67), — In fresh cultures the organism 
appears usually as a slightly curved rod somewhat shorter 

^T- -" £ * ^ •>. tea 



a • -.1* r/ 



.%# 



¥ 



<» ..v* v s ; 



Fig. 66. — Spirillum of Asiatic cholera, from a bouillon culture three weeks old, 
showing long and degenerate forms ; X iooo (Frankel and Pfeiffer). 

than the tubercle bacillus, but much thicker. The curving 
of the rod varies, being very marked in some individuals 
and absent in others. Sometimes two rods are joined end 
to end with their convexity pointing in opposite directions, 
or moderately long, undulating threads may be found. It 
seems probable that the curved rods represent the segments 
of a spirillum, and hence the name of the organism. 

In cultures some days old degenerated and atypical forms 
are found (involution forms). The organism is motile, and 
a single flagellum is attached to the end of the rod. 

1 Koch; Deutsche med. Wochenschr., 1884 and 188;. 



BACTERIOLOGICAL METHODS. 1 89 

It is not stained by Gram's method. 

Colonies on Gelatin Plates (Fig. 68). — After twenty-four to 
forty-eight hours at a temperature of 20 to 22 C. the 




Fig. 67. — Spirillum of Asiatic cholera, showing the flagella ; x 1000 (Gunther). 

largest colonies will appear as masses of indefinite granular 
material lying in circular areas of liquefied gelatin in which 
granular shreds are scattered. Within the next twenty-four 
hours the areas of liquefaction increase, and the colonies ap- 



• m 






Fig. 68. — Developmental stages of colonies of the spirillum of Asiatic cholera 
at 20 to 22 C. on gelatin ; x about 75 diameters (Abbott) : a, after sixteen to 
eighteen hours ; b, after twenty-four to twenty-six hours ; c, after thirty-eight to 
forty hours ; d, after forty-eight to fifty hours ; e, after sixty-four to seventy hours. 



pear under the low power " as a dense granular mass sur- 
rounded by an area of liquefaction through which can be seen 
granular prolongations of the colony, usually extending ir- 



190 PATHOLOGICAL TECHNIQUE, 

regularly between the periphery and the central mass " (Ab- 
bott), while the margin of the liquefied area is marked by 
delicate radiating filaments closely packed together. 

The colonies on agar-agar plates are not characteristic. 
Growth is rapid. 

Gelatin Stab. — Growth all along the line of inoculation 
with liquefaction at the surface in funnel form after forty- 
eight hours. The liquefaction proceeds in such a manner 
that the liquefied area has a smaller diameter at the surface 
than immediately beneath, and, owing to the fact that the 
liquefied gelatin does not fill the cavity, a space is left be- 
tween the surface of the medium and the surface of the lique- 
fied gelatin so that the appearance of an air-bubble is pro- 
duced. Along the deeper portions of the line of inoculation 
the liquefaction is slow. 

Bouillon. — Diffusely clouded. A thin pellicle forms on the 
surface after a time. 

Litmus-milk. — Turned red and coagulated. 

Indol-production. — In cultures in Dunham's pepton solu- 
tion or in the pepton solution of Koch (2 per cent, pepton 
and 1 per cent, sodium chlorid) a rose-color is produced by 
the addition of sulphuric acid alone. (Concentrated c. p. 
acid is to be employed, as in the test for indol-production by 
the bacillus coli communis.) The production of the rose-color 
without the addition of the sodium nitrite shows that nitrites 
as well as indol are formed by the growth of the organism 
in the pepton solution. The reaction can be obtained in 
cultures which have been but eight hours in the incubator. 

Potato. — Thin, dry, grayish-white growth which does not 
spread over the surface. 

Pathoge?iesis. — The pathogenic effects of the cholera 
spirillum are best shown by the inoculation of guinea-pigs. 
There are two methods of inoculation, as follows : 

I. The Method of Pfeiffer. — Scrape from the surface of a 
fresh agar-agar culture as much of the growth as will adhere 
to a platinum wire bent into the form of a small loop. Sus- 
pend this amount of material in 1 c.c. of bouillon, and inject 
the suspension into the peritoneal cavity of a guinea-pig 



BA CTERIOL O GICAL ME THODS. 



9 I 



by means of a hypodermic syringe. With virulent cultures 
this inoculation soon produces a fall in the temperature of 
the animal, which continues and becomes more marked, 
death occurring in from twelve to twenty-four hours. At 
the autopsy of the animal a clear fluid will be found in the 
peritoneal cavity and in the thorax. 

2. The Method of Koch. — This depends upon the fact that 
the animal may be infected through the alimentary canal, 
provided the acidity of the gastric juice be neutralized, this 
acidity being destructive to the cholera spirillum. 

A soft catheter is passed into the stomach of the animal 
through the mouth, and through this 5 c.c. of a 5 per cent, 
solution of sodium carbonate is injected. After ten or fifteen 
minutes 10 c.c. of a bouillon culture of the organism are in- 
jected through the catheter, and immediately afterward the 
animal receives subcutaneously 1 c.c. of the tincture of 
opium for every 200 grams of its body-weight. The object 
of this opium administration is to stop peristalsis, so that the 
organisms may be longer in contact with a given area of 
the mucous membrane of the intestine. The result of the 
inoculation first appears after about twenty-four hours. The 
animal then has no appetite and is listless. Later, paralysis 
of the hinder extremities appears, respiration is prolonged 
and weak, the heart-beats become feeble, and the body-tem- 
perature may become subnormal. Death usually occurs 
after the animal has been a few hours in this condition. 

At the autopsy the small intestine will be found to be in- 
jected and containing a flocculent colorless fluid in which 
comma bacilli are present in great numbers. 

Serum Reaction. — Cholera spirilla cease their motion, and 
aggregate together in clumps and masses when a bouillon 
culture of them is mixed with the serum of an animal immu- 
nized toward them. This phenomenon is called the serum 
reaction. Moreover, if cholera spirilla be placed in the peri- 
toneal cavity of an immunized guinea-pig, they will rapidly 
undergo disintegration, and will be destroyed. This is called 
Pfeiffer's phenomenon. 

Occurrence. — In the alvine dejections and in the intestinal 



192 PATHOLOGICAL TECHNIQUE. 

contents of cholera patients (Fig. 69). It apparently only 
rarely invades the circulating blood. Its presence in the 
vomitus may sometimes be shown. It has been found in the 
water-supplies during epidemics. 

The cholera spirillum is the representative of a large group 
of spirilla, many of which may be found in river waters. 
According to Abbott and Bergey, the only trustworthy 
method of distinguishing some of these from the true chol- 
era spirillum is their failure to manifest a " clump reaction " 
with the serum of an animal immunized to infection with the 
true cholera spirillum. 



Fig. 69. — Cover-glass preparation of a mucous fioccule in Asiatic cholera ; X 650 

(Vierordt). 

Bacteriological Diagnosis. 1 — Because of the manifold chan- 
nels which are open for the dissemination of this disease it is 
of the utmost importance that its true nature should.be recog- 
nized as quickly as possible, for with every moment of delay 
in its recognition opportunities for its spread are multiply- 
ing. It is essential, therefore, when employing bacteriological 
means in making the diagnosis to bear in mind those biolog- 
ical and morphological features of the organism that appear 
most quickly under artificial methods of cultivation, and which 
at the same time may be considered as characteristic of it — viz. 
its peculiar morphology and grouping ; the much greater rapidity 
of its growth over that of other bacteria with which it may be 
1 Abbott : Principles of Bacteriology. 



BA CTERIOL O GICAL ME THODS. 



193 



associated ; the characteristic appearance of its colonies on gela- 
tin plates and of its growth in stab-cultures in gelatin ; its property 
of producing indol and coincidently nitrites in from six to eight 
hours in pepton solution at 37 to 38 C. ; and its power of causing 
the death of guinea-pigs in from sixteen to twenty-four hours when 
introduced into the peritoneal cavity, death being preceded by 
symptoms of extreme toxemia, characterized by prostration and 
gradual and continuous falling in temperature of the animal's body. 

In a publication recently made by Koch 1 he called attention to 
a plan of procedure that is employed in this work in the Institute 
for Infectious Diseases in Berlin. In this scheme the points that 
have been enumerated are taken into account, and by its employ- 
ment the diagnosis can be established in the majority of cases of 
Asiatic cholera in from eighteen to twenty-two hours. In general, 
the steps to be taken and the points to be borne in mind are as 
follows. The material should be examined as early as possible 
after it has been passed : 

t. Microscopic examination. From one of the small slimy 
particles that will be seen in the semifluid evacuation prepare a 
cover-slip preparation in the ordinary way and stain it. If, upon 
microscopic examination, only curved rods or curved rods greatly 
in excess of all other forms are present, the diagnosis of Asiatic 
cholera is more than likely correct ; and particularly is this true 
if these organisms are arranged in irregular linear groups, with the 
long axis of all the rods pointing in nearly the same direction ; 
that is to say, somewhat as minnows arrange themselves when 
swimming in schools up stream (Koch). 

In 1886, Weisser and Frank 2 expressed their opinion upon the 
value of microscopic examination in these cases in the following 
terms : 

(a) In the majority of cases microscopic examination is suf- 
ficient for the detection of the presence of the comma bacillus in 
the intestinal evacuations of cholera patients. 

(^) Even in the most acute cases, running a very rapid course, 
the comma bacillus can always be found in the evacuations. 

(7) In general the number of cholera spirilla present is greater 
the earlier death occurs ; when death is postponed and the disease 
continues for a longer period, their number is diminished. 

(d) Should the patient not die of cholera, but from some other 
disease, such as typhoid fever, that may be engralted upon it, the 
comma bacilli may disappear entirely from the intestines. 

2. With another slimy flake prepare a set of gelatin plates. 
Place them at a temperature of from 20 to 22 C, and at six- 
teen, twenty-two, and thirty-six hours observe the appearance of 
the colonies. Usually at about twenty-two hours the colonies of 
this organism can easily be identified by one familiar with them. 

3. With another slimy flake start a culture in a tube of pepton 

1 Zeitschrift f. Hygiene u. Infect ioiskrankheiten, Bd. 14, 1S93. 

2 Ibid., Rd. 1, p. 397. 
13 



194 PATHOLOGICAL TECHNIQUE. 

solution — either the solution of Dunham or, as Koch proposes, a 
solution of double strength of that of Dunham (Witte's pepton is 
to be used, as it gives the best and most constant results). Place 
this at 37 to 38 C, and at the end of from six to eight hours 
prepare cover-slips from the upper layers (without shaking) and 
examine them microscopically. If comma bacilli are present and 
capable of multiplication, they will be found in this locality in 
almost pure culture. After doing this prepare a second pepton 
culture from the upper layer, also a set of gelatin plates, and with 
what remains make the test for indol by the addition of 10 drops 
of concentrated sulphuric acid for each 10 c.cm. of fluid con- 
tained in the tube. If comma bacilli are growing in the tube, 
the rose color characteristic of the presence of indol should 
appear. 

By following this plan "a bacteriologist who is familiar with 
the morphological and biological peculiarities of this organism 
should make a more than probable diagnosis at once by micro- 
scopic examination alone, and a positive diagnosis in from twenty 
to, at the most, twenty-four hours after beginning the examination' ' 
(Koch). 

There are certain doubtful cases in which the organisms are 
present in the intestinal canal in very small numbers, and micro- 
scopic examination is not, therefore, of so much assistance. In 
these cases plates of agar-agar, of gelatin, and cultures in the pep- 
ton solution should be made. 

The plates of agar-agar should not be prepared in the usual 
way, but the agar-agar should be poured into Petri dishes and al- 
lowed to solidify, after which one of the slimy particles may be 
smeared over its surface. The comma bacillus being markedly 
aerobic., develops very much more readily when its colonies are 
located upon the surface than when they are in the depths of the 
medium. A point to which Koch calls attention in connection 
with this step in the manipulation is the necessity for having the 
surface of the agar-agar free from the water that is squeezed from 
it when it solidifies, as the presence of the water interferes with 
the development of the colonies as isolated points and causes 
them to become confluent. To obviate this, he recommends that 
the agar-agar be poured into the plates and the water allowed 
to separate from the surface at the temperature of the incubator 
before they are used. It is wise, therefore, when one is liable 
to be called on for such work as this to keep a number of 
sterilized plates of agar-agar in the incubator ready for use, just 
as sterilized tubes of media are always ready and at hand. The 
advantage of using the agar plates is the higher temperature 
at which they can be kept, and consequently a more favorable 
condition for the development of the colonies. As soon as iso- 
lated colonies appear they should be examined microscopically for 
the presence of organisms having the morphology of the one for 
which we are seeking, and as soon as such is detected gelatin plates 



BACTERIOLOGICAL METHODS. 195 

and cultures in pepton solution (for the indol reaction) should be 
made. The pepton cultures started from the original material 
should be examined microscopically from hour to hour after the 
sixth hour that they have been in the incubator. The material 
taken for examination should always come from near the surface 
of the fluid, and care should be taken not to shake the tube. As 
soon as comma bacilli are detected in anything like considerable 
numbers in the upper layers of the fluid, agar-agar plates and 
fresh pepton cultures should be made from them. The colo- 
nies will develop on the agar-agar plates at 37 C. in from ten 
to twelve hours to a size sufficient for recognition by microscopic 
examination, and from this examination an opinion can usually 
be given. This opinion should always be controlled by cultures 
in the pepton solution made from each of several single colonies, 
and finally the test for the presence or absence of indol in these 
cultures. 

In all doubtful cases in which only a few curved bacilli are pres- 
ent or in which irregularities in either the rate or mode of their 
development occurs, pure cultures should be obtained by the 
agar-plate method and the method of cultivation in pepton solu- 
tion as soon as possible, and their virulence tested upon animals. 
For this purpose cultures upon agar-agar from single colonies 
must be made. From the surface of one of such cultures a good- 
sized wire-loopful should be scraped, and this broken up in about 
1 c.c. of bouillon, and the suspension thus made injected by 
means of a hypodermic syringe directly into the peritoneal cavity of 
a guinea-pig of about 350 to 400 grams weight. For larger animals 
more material should be used. If the material injected is from a 
fresh culture of the cholera organism, toxic symptoms at once 
begin to appear ; these have their most pronounced expression in 
the lowering of temperature, and if one follows this decline in 
temperature from time to time with the thermometer, it will be 
seen to be gradual and continuous from the time of injection to 
the death of the animal, which occurs in from eighteen to twenty- 
four hours after the operation. 1 

In general, this is the procedure employed at Berlin in the In- 
stitute for Infectious Disease under Koch's direction. 

Bacillus of Anthrax. 2 — Blood-serum. — Irregularly 
rounded colonies, several mm. in diameter after twenty-four 
hours in the incubator. The colonies are grayish, finely 
granular, and have the appearance of being made up of a 
dense network of delicate fibrillar. The blood-serum is 
slowly liquefied. 

1 Pfeiffer : loc. cit. 

2 Pasteur: Bull. Acad. de. Med., Paris, T. viii., 1879; Koch: F. Conns 
Beitr. z. Biol. d. Tf., Bd. 2, 1876. 



196 



PA THO L O GICA L TE CHNIQ UE. 



Morphology. — The organism grows in long segmented 
threads, the segments varying in length, but usually being 
two or three times as long as broad and having square or 
slightly concave ends. These segments represent the bacillus, 
which is among the largest of the bacteria (Fig. 70). 

Pathogenesis. — Mice, guinea-pigs, and rabbits inoculated 
subcutaneously die with a general invasion of the blood by 
the organism. Mice are most susceptible to the infection, 
dying in about twenty-four hours, while guinea-pigs and 
rabbits survive longer. 




Fig. 70. — Bacillus of anthrax : portion of a colony three days old upon a gelatin 
plate; X iooo (Frankel and Pfeiffer). 



In all these animals the most striking lesion is a large soft 
spleen, and in the guinea-pig also an extensive inflammatory 
edema of the subcutaneous tissues. On microscopic exam- 
ination the bacilli will be found in the organs and blood of 
the heart. If the animal has been dead some time, the 
number of bacilli present in these situations will be very 
great, owing to the post-mortem growth. It is characteristic 
of the bacillus of anthrax in cover-slip preparations from in- 
fected tissues that it should have a narrow capsule (Fig. 71) 



BA CTERIOL O GICAL ME THODS. 



197 



and show square or slightly concave ends. The capsule is 
not present in cultures. 

Stained by Gram's method. Not motile. 

Forms oval spores in the middle of the short segments or 
rods. The spores may be seen in blood-serum cultures after 
forty-eight hours in the incubator (Fig. 72). 

Gelatin Stab. — Growth along the line of stab, with radiat- 
ing filaments extending laterally into the gelatin, which is 
slowly liquefied in funnel form (Fig. 73). 

Bouillon. — Growth in the form of cotton-like flakes and 
filamentous masses. No clouding of the medium. 

Agar-agar. — Matted network of translucent filaments. 



>*»» x 



^. ,V>-H \ \ \ '■■■■' - X 






y 

FIG. 71. — Bacillus of anthrax from spleen of a mouse (L. Frothingham). 



Under a lower magnifying power the growth is seen to be 
made up of twisted and contorted masses of filaments, giv- 
ing the appearance of curled hair (Fig. 74). 

Potato. — Grayish-white, rather thick, dry layer, having the 
appearance of frosted glass. 

Occurrence. — In malignant pustules, wool-sorter's disease, 
and intestinal anthrax. Found in the blood of animals dead 



PA THOL GICA L TE CHNIQ UE. 



of anthrax. In man the infection is usually localized at 
first at the point of inoculation, either on the skin or on the 



* 







4 # 



r. a 



I % - 



^ 



FlG. 72. — Bacillus of anthrax, stained to show the spores; X 1000 (Frankel and 

Pfeiffer). 

mucous membrane of the air-passages or intestinal tract. 
Later, a general invasion of the blood may occur and a fatal 




FlG. 73. — Bacillus of anthrax : gelatin stab-culture seven days old (Giinther). 

septicemia result. The organism or its spores may be pres- 
ent in wool or hides, and infection may take place from these. 
Diagnosis. — The bacilli may be found by the cover-glass 



BACTERIOLOGICAL METHODS. 199 

examination of the contents of the small blebs and vesicles. 
The bacillus of anthrax may be identified by its morphology 
(see p. 196), its special characteristics being its large size and 
its square or concave extremities. 

The inoculation of a mouse at the root of the tail with 
some of the material from the pustule, and the production 
of the characteristic fatal septicemia, will render the identifi- 
cation certain. 







Fig. 74. — Colony of bacillus of anthrax, slightly magnified (Fliigge). 



Bacillus Pyocyaneus (Bacillus of Green Pus). 1 — 

Colonies on blood-serum grow rapidly, are not especially 
characteristic in form, and liquefy the medium, imparting to 
it a dark greenish color. 

Morphology. — Small bacilli with rounded ends (Fig. 75). 

Decolorized by Gram's method (Welch). Motile, and is 
provided with a flagellum at one end. Does not form spores. 

Gelatin Stab. — Liquefaction in funnel form, with green 
fluorescence of the upper portions of the medium. The 
liquefied gelatin is densely clouded, and there may be a 
viscid pellicle on the surface. 

1 Gessard: Annates de V Inst i tut Pasteur, T. 5, 1S91. 



200 



PA THOL GICAL TECHNIQ UE. 



Agar-agar Stab. — A green fluorescence in the upper layers 
of the medium, which later becomes a dark blue-green. 

Potato. — Slightly elevated, brownish, viscid layer. The 
potato in some cases assumes a green color, in others a 
brown color. In some cultures the potato when touched 
with the platinum wire takes on a green color at the point 
touched. This is the so-called " chameleon phenomenon," 
and it is best observed in cultures several days old. 

Bouillon. — The growth is in the form of flocculi and a 
delicate surface pellicle. The fluid acquires a green color. 

Litmus-milk. — Acid reaction with coagulation. 

Dunham's Pepton Solution. — Indol is produced. 

Colonics on Gelatin Plates (Fig. 76). — Development is rapid. 
"Young colonies are provided with a fringe of delicate fila- 




Fig. 75. — Bacillus pyocyaneus showing flagella, from a preparation stained by 
Dr. Hugh Williams; x 2000 (Wright and Brown). 

ments about their periphery. ... As growth progresses and 
liquefaction becomes more advanced, the central mass of the 
colony sinks into the liquefied depression, while at the same 
time there is an extension of the colony laterally. ... At this 
stage the colony, when slightly magnified, may present vari- 
ous appearances, the most common being that shown in Fig. 
76. The gelatin between the growing colonies takes on a 
bright yellowish-green color, but, as growth is comparatively 
rapid, it is quickly entirely liquefied, and one often sees the 
colonies floating about in the pale-green fluid." 1 

Pathogenesis. — Subcutaneous inoculation of guinea-pigs 
and rabbits with I c.c. of a virulent bouillon culture may 
produce purulent infiltration and inflammatory edema of the 

1 Abbott : Principles of Bacteriology. 



BA CTERIOL O GICAL ME THODS. 



201 



tissue about the point of inoculation, and death may follow 
in eighteen to thirty-six hours. Intraperitoneal inoculation 
may result in a sero-fibrinous or purulent peritonitis with 
fatal result. In fatal inoculations the bacillus is found in the 
various viscera, but not in great numbers. Animals inocu- 
lated with small amounts may survive with merely local 
lesions, and an immunity may be produced. 

Several varieties of this bacillus have been described, but their 
differences do not seem to be of sufficient importance to justify 
their separation into distinct species. 





Fig. 76. — Bacillus pyocyaneus : colonies upon gelatin (Abbott). 

Occurrence. — " Is widely distributed, occurring often on the 
human skin, in the feces, and outside of the body. In wounds, 
stains the dressings bluish-green and produces a somewhat 
characteristic offensive odor. 

" Increases suppuration of wounds, usually with little con- 
stitutional disturbance. Is found not infrequently in perfora- 
tive peritonitis and appendicitis, sometimes in phlegmons, 
otitis media, broncho-pneumonia, and inflammation of serous 
membranes, associated usually with other bacteria. 

" It was found by H. C. Ernst in tuberculous pericarditis. 
Often found in diarrheal and dysenteric discharges. May 
cause general infection in human beings. With or without 
general infection it may cause hemorrhagic and necrotic en- 
teritis, a form of pyocyaneous infection in human beings which 
we have repeatedly observed at autopsy. Instances of in- 



202 PATHOLOGICAL TECHNIQUE. 

vasion of the body from wounds by the bacillus pyocyaneus 
have not been observed " (Welch). 

Bacillus of Bubonic Plague. — Morphology. — In the 
tissues the organism occurs as a medium-sized short bacillus 
with rounded ends. In cultures its size and length vary 
and its median portion may be swollen so that an ovoid 
form is produced ; it may grow in pairs and in chains, 
and it may occur as long, thread-like forms. Involution 
forms of elliptical or round shape, and often of large size, 
sometimes resembling yeast-cells, are frequent in old cult- 
ures or in cultures on special media. These involution 
forms are easily produced by cultivation on agar-agar con- 
taining 2^ to 3^ per cent, of sodium chlorid. 




FIG. 77. — Bacillus of bubonic plague (Yersin). 

Staining. — The organism stains with the usual aniline dyes, 
and is decolorized by Gram's method of staining. In the 
tissues it stains more deeply at its extremities than at its 
central portions, and it sometimes appears to possess a cap- 
sule. The polar staining may sometimes be brought out 
in cultures by weak staining solutions or by decolorization 
by alcohol. It is not motile, and it does not form spores. 

Gelatin Plates. — The colonies on the surface appear after 
twenty-four to forty-eight hours at 22° C. They are flat, 
round, and white or yellowish white in color. Under a low 
magnifying power the central portion of the colony is gran- 



BACTERIOLOGICAL METHODS. 203 

ular, while the marginal portion is clear. The colonies do 
not spread over the surface of the medium. 

Gelatin Stab. — Growth all along the line of inoculation 
with the formation of a layer of growth at the surface of a 
whitish color. There is no liquefaction of the gelatin. 

Gelatin Slants. — A whitish or slightly yellowish layer 
presenting nothing characteristic. 

Agar-agar Plates. — The colonies on the surface appear 
first as dew-drops, and have already attained their maximum 
development after twenty-four to forty-eight hours in the 



,7,f 

i 







FlG. 78. — Bacilli of plague and phagocytes, from human lymphatic gland ; X 800 

(Aoyama). 

incubator. They will then grow white in color, and present 
an opalescent or iridescent margin. Under the microscope 
they are distinctly granular. Considerable difference in size 
may be observed among the colonies. The larger colonies 
are said to be less virulent for animals than the smaller 
colonies, and it is claimed that these larger colonies when 
transplanted give rise to large colonies again. 

Agar-agar Slant. — The colonies tend to become conflu 
ent, and the growth is somewhat viscid. 

Bouillon. — The fluid usually remains clear, and the growth 
appears in the form of a granular or flocculent sediment 



204 PATHOLOGICAL TECHNIQUE. 

which may here and there adhere to the wall of the tube. 
In bouillon cultures richly inoculated and retained in a per- 
fectly and undisturbed position at room-temperature for 
some days a characteristic appearance is produced. In 
twenty-four to forty-eight hours islands of growth appear 
underneath the surface in the form of flakes. In the next 
twenty-four to forty-eight hours there grow down into the 
fluid from the flakes long, stalactite-like masses, the liquid 
remaining clear. In four to six days the islands of growth 
have become more compact and solidified. If the flask be 
now slightly disturbed, the islands fall to the bottom, bring- 
ing with them the stalactite-like growths. The latter are 
very fragile. In addition to these appearances there is a 
deposit of growth on the wall of the flask and at the bottom, 
as well as a ring of growth on the margin of the surface of 
the liquid. 

Milk. — Growth without coagulation. 

No production of indol. 

In neutral litmus bouillon the blue color is changed to red. 

There is no odor, and no pigment production. 

The organism is aerobic. 

It remains alive in cultures for five to six weeks at least. 

Growth occurs at all temperatures from 4 C. to 37 C. 
The best temperature for growth is 30 to 32 C. 

Pathogenesis. — The organism is pathogenic for a great 
variety of animals, including mice, rats, guinea-pigs, and 
rabbits. In these animals death generally follows in from 
two to six days after subcutaneous inoculation. The lesions 
produced are hemorrhagic edema at the seat of inoculation, 
enlargement of the lymphatic glands with more or less 
hemorrhage, enlargement of the spleen and its follicles. 
The bacilli are present in large numbers in the enlarged 
lymphatic glands and in the internal organs ; they are less 
numerous in the blood. Rats and certain other animals 
may be infected by feeding. Pigeons, chickens, and cattle 
are immune. 

Occurrence. — The bacillus is found in large numbers in 
the buboes, pustules, pulmonary lesions, and other localized 



BACTERIOLOGICAL METHODS. 205 

lesions of the bubonic plague. It also may be found in 
larger or smaller numbers in the blood and internal organs 
generally, and it may be present in the sputum, bile, and 
alvine discharges. The pus of the buboes which break 
spontaneously may be sterile. The organism may be 
demonstrated in the circulating blood of cases of plague. 

Bacteriological Diagnosis. — In cases of suspected plague 
the bacillus is to be sought for in the blood and in the 
buboes. In cases of pneumonia the sputum especially is 
to be examined. In the examination cultures as well as 
cover-glass preparations are to be used. 

Perhaps the most certain method of identification of the 
bacillus is the inoculation of the mucous membrane of the 
nose of the rat. The simple rubbing of a portion of the 
culture upon the mucous membrane appears to be sufficient 
to produce a fatal result in the rat if the culture is that of 
the genuine bacillus. As a culture-medium agar-agar or 
blood-serum is to be used in cases where there is no mixed 
infection. If there is mixed infection of the material to be 
examined, gelatin surface-cultures are to be made. 

The inoculation of animals for diagnostic purposes should 
be made with the greatest precaution to prevent the spread 
of the disease. 

Bacillus of Influenza. 1 — Morphology. — Very small ba- 
cilli, with rounded ends and of variable length, sometimes 
growing into long forms, more or less bent or curved (see 
Fig. 79). 

Stains more deeply at the ends than in the middle, and in 
the long forms shows irregularity of staining. The faintly 
stained areas are very sharply defined, as in the case of the 
typhoid bacillus. 

Li cover-glass preparations from bronchial secretions (see 
Fig. 80) the bacillus appears smaller and less plump than 
it does in preparations from cultures. It also does not show 
irregularities in staining. 

Cultivation. — Does not grow in the ordinary culture-media, 
but maybe cultivated on agar- agar "slants," the surfaces 

1 Ffeiffer: Zeitschrift /. Hygiene u. Infectionskrankheiten, Bd. 13. 1S93. 



206 PATHOLOGICAL TECHNIQUE. 

of which have been smeared with a few drops of sterile 



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Fig. 



79. — Influenza bacilli from a culture on blood-agar ; X 2000 (Wright and 
Brown). 




Fig. 80. — Bacilli of influenza in a leucocyte in a cover-glass preparation from 
sputum. A pneumococcus also in the same leucocyte and other pneumococci 
free. The small size of the bacillus of influenza will be apparent by comparison 
with the pneumococci ; X 2000 (Wright and Brown). 

blood. The blood of man, rabbits, guinea-pigs, pigeons, or 
frogs will serve for this purpose, the best growth being 



BACTERIOLOGICAL METHODS. 



207 



obtained with pigeon's blood. The blood may be ob- 
tained from a needle-prick, and spread over the surface 
of the agar-agar by means of the platinum loop. The skin 
should be previously thoroughly washed with alcohol and 
ether, and the first drops of blood should not be used. 
Human blood is best obtained from the lobe of the ear 




Fig. 81. — Bacillus of influenza: colonies on blood agar-agar; low magnitying 
power (Pfeiffer). 

or from the finger. Tubes thus prepared are only rarely 
contaminated. 

Colonies. — After twenty-four hours in the incubator the 
colonies appear as minute colorless, glassy, transparent 
points resembling small drops of dew. They never attain 
any size, and do not become confluent. They are barely 
visible to the unpractised eye, and require a low magnifying 
power to be seen clearly. Under the low magnifying power 
they are translucent, homogeneous, not granular, and cir- 
cular in outline (Fig. 81). 

Decolorized by Gram's method. Not motile. Will not 
grow without oxygen. 



208 PATHOLOGICAL TECHNIQUE. 

Pathogenesis. — The ordinary laboratory animals are not 
susceptible to infection with this organism. 

Occurrence. — Found in the exudate of the respiratory tract 
in influenza, frequently inside of leucocytes (Fig. 80). It 
may be present in the small bronchi and in the exudate of 
broncho-pneumonia in this disease. It has been observed in 
purulent meningitis secondary to influenza. 

F. T. Lord, 1 working in the Laboratory of the Massachusetts 
General Hospital, found influenza bacilli in 60 of 100 unselected 
specimens of sputa repeatedly negative for tubercle bacilli. In 29 
of these 60 cases the bacilli were present in great numbers. 
Eleven cases were of acute and 18 of chronic inflammation of the 
respiratory tract. In the chronic cases he demonstrated the per- 
sistence of influenza bacilli in the sputum for months or years. 

Lord believes that influenza bacilli are very commonly present 
in sputa apart from epidemics of influenza, and that chronic infec- 
tion with influenza bacilli is not infrequently mistaken clinically 
for tuberculosis. 

Diagnosis. — Microscopical examination of cover-glass 
preparations of the bronchial sputum shows very small, 
short, round-ended bacilli, often in very large numbers and 
frequently in the pus-cells. These bacilli frequently occur 
in pairs and resemble pairs of cocci. Their ends may be 
more deeply stained than the central portions. For the 
staining of cover-glass preparations of the sputum PfeifTer 
recommends that a very dilute carbol-fuchsin solution be 
applied for five to ten minutes. The cover-glass preparation 
is to be made from a distinctly purulent portion of the 
sputum. Staining with Loffler's methylene-blue solution 
also gives good results. See also W. H. Smith's method 
for staining the capsule of the pneumococcus, page 142. 

The bacillus of influenza may be cultivated from the 
sputum by breaking up a small portion of a distinctly puru- 
lent character in 1 or 2 c.c. of bouillon, and then spreading 
a platinum loopful of the suspension over the surface of a 
blood-agar-agar slant, which is then placed in the incubator. 
After eighteen to twenty-four hours the characteristic col- 
onies may be visible with the aid of a hand-lens. These 

1 Boston Medical and Surgical Journal, December iS, 1902. 



BA C TERIOL O GICA L ME THODS. 



209 



should not grow in ordinary media unless blood or hemo- 
globin be present, and should have the morphology of the 
bacillus of influenza. 

F. T. Lord obtains the best results by using as a culture-medium 
1 part sterile horse-blood and 2 parts nutrient agar-agar in 
" slant" tubes. The blood is mixed with fluid agar -agar at 40 
C. The colonies of the influenza bacilli may attain a diameter 
of more than a millimeter on this medium. The horse-blood may 
be easily obtained from any antitoxin plant and may be kept on 
hand in test-tubes for months without impairment of its utility for 
cultural purposes. 

Bacillus of Glanders (Bacillus Mallei). 1 — Blood- 
serum. — Rounded, elevated, colorless, viscid-looking colonies, 
growing slowly and becoming well developed after thirty-six 
hours in the incubator. They may attain a diameter of 2 or 
3 mm., and after a time they assume a brownish tint. 




Fig. 82. — Glanders bacilli from a young culture on potato ; X 2000 (Wright and 

Brown). 

Morphology. — Bacilli of medium size, variable in length, 
having round or conical ends, and frequently showing faintly 
stained areas in their protoplasm (Fig. 82). The larger forms 
of the bacillus are usually slightly bent or wavy in outline. 
Slight irregularities in shape may be observed. The mor- 
phology varies considerably on different culture-media. 
In cover-glass preparations from the lesions the bacilli 
1 Loffler : Arbeiten a. d. Kais. Gesundkeitsamte, Bd. 1, 1SS6. 
14 



2IO PATHOLOGICAL TECHNIQUE. 

usually appear somewhat longer and thicker than the tuber- 
cle bacillus, and show numerous sharply defined, unstained 
or faintly stained areas in their protoplasm (Fig. 83). They 
have rounded or conical ends, and are sometimes slightly 
irregular in shape. As a rule, they are present in small 
numbers. If Loffler's methylene-blue solution is used for 
staining the cover-glass, it should be heated ; if carbol- 
fuchsin is used, it should be followed by a slight decolori- 
zation with 95 per cent, alcohol to better differentiate the 
bacilli. 

Potato. — After thirty-six hours in the incubator a rather 
thick, colorless, viscid-looking layer appears,, which soon 




FIG. 83. — Glanders bacilli in a cover-glass preparation from a lesion in a 
guinea-pig, showing the marked irregularity in the staining of the bacilli ; X 2000 
(Wright and Brown). 

assumes a brownish tint and resembles honey in appearance. 
Later the brown color changes to a dark reddish-brown, 
and the growth becomes thicker and more opaque, while 
the potato takes on a dark-gray color. 

Pathogenesis. — When inoculated subcutaneously into 
guinea-pigs, the characteristic results are swelling and inflam- 
mation of the scrotum, appearing after a variable number of 
days, often after a week. 

The animals usually survive several weeks, with ulceration 
at the point of inoculation. The lesions produced consist 
in suppurative processes or abscess-formations in or about 
the testes, in the lymph-glands, in the anterior nares, about 
the joints, and in other situations, besides small grayish 



BACTERIOLOGICAL METHODS. 211 

nodules or areas in the viscera — the so-called " glanders 
tubercles." The suprarenal capsules usually show red 
areas, and they may be enlarged. On microscopical exami- 
nation the small nodules as well as the extensive suppura- 
tive areas will be found to be composed of necrotic material 
containing leucocytes and fragments of chromatin. The 
distribution and extent of the lesions vary with each animal, 
but the involvement of the testis or its membranes is prac- 
tically constant and pathognomonic of the bacillus of glan- 
ders. This involvement of the testis may consist, in early 
cases, in the presence of yellow foci in or about the tunica 
vaginalis, or in later cases the organ may show large yellow 
areas with purulent softening. 

Intraperitoneal inoculation with virulent cultures may be 
followed by death within forty-eight hours, with fibrinous 
exudate on the peritoneum in which minute grayish nodules 
are seen. The nodules are made up of a material which is 
apparently mainly dead or degenerated leucocytes and des- 
quamated peritoneal endothelium, together with many chro- 
matin fragments. 

In these acute cases also microscopical examination of 
the spleen and liver may show the presence of small nodules 
identical in structure with those seen in the more chronic 
cases. For the purpose of producing with cultures the 
characteristic lesions of the testis or its coverings it is better 
to inoculate the animal subcutaneously, for in the rapidly 
fatal intraperitoneal inoculations with virulent cultures these 
may not show any marked changes. 

The bacilli may be cultivated from the lesions, but not 
from the blood of the heart, in the chronic cases. They 
may be present in the blood of the heart, however, in small 
numbers in rapidly fatal infections following intraperitoneal 
inoculation. 

Field-mice may die from subcutaneous inoculation in 
about seventy -two hours. The most conspicuous lesion pro- 
duced is enlargement of the spleen, with the presence in it of 
minute grayish nodules. White mice are immune. Rabbits 
are not so susceptible as guinea-pigs to the infection. 



212 PATHOLOGICAL TECHNIQUE. 

Decolorized by Gram's method. Not motile. Spore- 
formation not probable. Rate of growth is slow. 

Bouillon. — Diffusely clouded, with the formation of a 
viscid sediment. 

Litmus-milk. — Gradually turned red and coagulated. 

Agar-agar and Gelatin. — Growth not especially charac- 
teristic. 

Occurrence. — Found in the lesions of glanders and of 
farcy, and may invade the blood-stream in small numbers 
in acute cases of infection. Grows in the tissues in clumps 
or groups as well as scattered. In lesions on exposed sur- 
faces it may be accompanied by the pyogenic cocci. We 
have succeeded in demonstrating the presence of the bacillus 
in the sputum of a case of human glanders by inoculation 
of a guinea-pig with the sputum. 

Diagnosis. — In a case of suspected glanders the dis- 
charges from sinuses or ulcerated surfaces, or the contents 
of pustules, are to be examined for the presence of the 
bacillus of glanders by the usual methods. 

The material for examination may be collected on "swabs." 
With this a guinea-pig is to be inoculated and cultures and 
cover-glass preparations are made. If the material be from 
sinuses or ulcerated surfaces, the isolation of the bacillus by 
cultures will be difficult, owing to the presence of other or- 
ganisms. The guinea-pig is to be inoculated in the peri- 
toneal cavity by introducing the infected swab into it through 
an incision in the abdominal wall, or by injecting about I 
c.c. of a suspension in bouillon of the suspected material 
into the peritoneal cavity with a hypodermic syringe. 

If the bacillus of glanders is present, the scrotum will 
usually show the characteristic swelling and inflammation in 
the course of three or four days, and death will occur after 
some weeks. In some cases the animal may die in thirty- 
six or forty-eight hours. In any case the characteristic 
lesions of glanders will be found as described elsewhere, 
and the bacillus may be isolated from them by cultures. 
The spleen will practically always yield glanders bacilli in 
pure culture even if no macroscopical lesion can be made out. 



BA CTERIOL O GICA L ME THODS. 



213 



In cultures the organism should show those character- 
istics of morphology, of culture, and of pathogenesis which 
have been described above. 

Bacillus of Chancroid (Bacillus of Ducrey). — In 

smears from the lesions the bacilli appear as short, round- 
ended rods, about 1.5 fi long and 0.5 fJ. thick, occurring 
characteristically but not always in chains. The middle 
portion of the rods does not stain so deeply as the ends. 
The bacilli are decolorized by Gram's method of staining, 
and are not motile. The following description of the cul- 




FlG. 84. — Bacillus of chancroid in smear preparation from pus (Lincoln Davis ; 
photo by L. S. Brown). 

tural peculiarities of the chancroid bacillus are based on the 
observations of Dr. Lincoln Davis in the Laboratory of the 
Massachusetts General Hospital. 1 

The bacillus does not grow on the ordinary culture- 
media, but may be cultivated in blood or in media contain- 
ing one-third its volume of blood. It is essential that the 
blood be fresh. In tubes containing blood, or a mixture of 
bouillon and blood, after twenty-four hours in the incubator, 
the growth appears as whitish flocculi at the bottom of the 
tube. These flocculi are composed of tangled chains of the 
bacilli, the chains being often of extreme length. The 

1 " Observations on the Distribution and Culture of the Chancroid Ba- 
cillus," Journal of Medical Research, vol. ix., p. 401. 



214 



PA THOL O GICA L TE CHNIQ UE. 



individual bacilli, as a rule, have the same morphology and 
staining reactions as in the smears from lesions, but occa- 
sionally long or even filamentous forms may be seen. On 
the surface of slant tubes, composed of a mixture of fresh 
blood and agar, the bacillus forms, after forty-eight hours in 
the incubator, small, rounded, grayish colonies difficult to 
pick up with the platinum wire, because they tend to glide 
before it. The bacilli from these colonies appear in smear 
preparations in short chains and singly. Involution forms 
are early apparent among the bacilli in all cultures. The 
bacillus dies out in cultures after about three days. Upon a 
monkey of the genus Macaccus, small ulcerations in the 
skin were produced by inoculation with cultures. 










x*Z~^f^ 




Fig. 85. — Bacillus of chancroid from culture (Lincoln Davis ; photo by 
L. S. Brown). 

Method of Isolation from the Lesions. — Dr. Davis found 
that pure cultures were readily obtained by inoculating a 
small quantity of freshly drawn human blood in small tubes 
with material from the lesions, the fresh blood apparently 
inhibiting or destroying other bacteria. These small tubes 
containing blood are most easily prepared in a way devised 
by J. H. Wright. A small glass tube, about 5 or 6 cm. long 



BACTERIOLOGICAL METHODS. 21 5 

and 4 or 5 mm. in internal diameter, is drawn out into a fine 
caliber at one end, and is then sterilized throughout in the 
gas-flame. When cool, the pointed extremity of the tube is 
immersed in the blood obtained from a needle-prick in the 
skin of the dorsum of the thumb near the nail, and then by- 
manipulation of the tube the blood is caused to flow into it. 
In this way a sufficient quantity — say, o.2 to 0.5 c.c. — is 
easily collected in the tube, after which the pointed end is 
sealed in the flame and the tube is ready to be inoculated. 
The other end of the tube is plugged with cotton, which is 
impregnated with paraffin to prevent evaporation. The 
skin, before being pricked, is sufficiently cleansed by soap 
and water, followed by alcohol. A small tourniquet is 
applied about the base of the thumb, to increase the flow of 
blood from the needle-prick. 

Bacillus Proteus (Proteus Vulgaris).— Morphology. — 
Bacilli of very variable length, sometimes appearing like 
cocci or as filaments. 

Motile, being provided with terminal flagella. Does not 
stain by Gram's method. 

Colonies in Gelatin. — Rapid growth with liquefaction of 
the gelatin. In a medium containing 5 per cent., instead of 
10 per cent., of gelatin prolongations from the margins of 
the colonies may be formed. These may become separated 
from the mother colonies and form daughter colonies. 
Motions may be observed in these prolongations. 

Gelatin Stab. — Rapid liquefaction along the line of inocu- 
lation with cloudiness of the liquefied gelatin and a floccu- 
lent deposit. 

Agar-agar Slant. — Widely spreading, thin, moist, grayish- 
white layer. 

Potato. — Dirty white, moist layer. 

Litmus-milk. — Turned pink and slowly coagulated. 

Odor. — The cultures generally have a putrefactive odor. 

Pathogenesis. — Intravenous, intraperitoneal, or intramus- 
cular inoculations of rabbits may produce death in twenty- 
four to thirty-six hours after moderately large doses. Liq- 
uefied gelatin-cultures are said to be more virulent than 



216 



PA THOL O GICA L TE CHNIQ UE. 



bouillon cultures. Guinea-pigs seem to be less susceptible 
than rabbits to infection with this organism. 

Occurrence. — This bacillus and its varieties are among the 
most common and widely distributed putrefactive bacteria. 
It occurs in the intestinal contents. In pathological exam- 
inations it may be found in peritonitis and in abscesses, 
usually associated with other bacteria. It may also invade 
the circulating blood. 

The so-called "proteus group" includes several varieties of 
similar organisms — viz. the proteus vulgaris, the proteus mirabilis, 
and the proteus Ze?ikeri. The latter does not liquefy the gelatin, 
while the proteus mirabilis liquefies it slowly. 

Bacillus MUCOSUS CapSUlatUS. 1 — Blood-serum. — After 
twenty-four to thirty-six hours in the incubator the colonies 




FIG. 86. — Bacillus mucosus capsulatus, from the sputum of a pneumonia 
patient; x iooo (Frankel and Pfeiffer). 



appear as translucent, colorless, rounded, convex elevations, 
resembling drops of mucus. If few in number, they may 
attain a diameter of 2-3 mm. They are viscid, and when 
touched with the platinum wire may be drawn out into 

1 Friedlander: Fortschritte der Median, 1 883, Bd. I, S. 715 ; C. Fricke : 
Zeitschrift f. Hygiene u. Infectionskrankheiten, Bd. 23, 1896. 



BACTERIOLOGICAL METHODS. 2\J 

threads. The water of condensation may become thick or 
viscid from the growth of the organism in it. 

Morphology. — Bacilli of moderate size, usually two or 
three times as long as broad, with rounded ends, occurring 
frequently in pairs and sometimes in long forms. Occasion- 
ally in cultures it shows a wide capsule. The capsule, how- 
ever, is best shown in cover-glass preparations from infected 
tissues (Figs. 86, 88). 

Pathogenesis. — White mice, rabbits, and guinea-pigs die 
from septicemia in a short time after inoculation, the capsule 
bacilli being present in the organs and blood of the heart in 
large numbers. 




Fig. 87. — Bacillus mucosus capsulatus, from a culture ; x iooo (Wright and 

Brown). 

White mice die in twenty-four hours to three days. Rab- 
bits inoculated in the ear-vein and guinea-pigs inoculated in 
the peritoneal cavity may die within twenty-four hours. 

Subcutaneous inoculation of the animals last named 
leads only to local suppuration. The lesions produced by 
this organism consist in marked congestion of the super- 



2l8 PATHOLOGICAL TECHNIQUE. 

ficial veins, hemorrhage into the lymphatic glands, and en- 
largement and softening of the spleen. In the guinea-pig a 
hemorrhagic condition of the supra-renal capsules is present, 
and in the peritoneal cavity there may be a small amount 
of clear, rather viscid fluid containing the bacilli in large 
numbers. 

The organs on microscopic examination may show pecu- 
liar areas in which the cells and nuclei are shrunken and in 
which the bacilli are aggregated. 



Fig. 88. — Bacillus mucosus capsulatus in blood; x iooo (Frankel and Pfeiffer). 

Decolorized by Gram's method. Not motile. Does not 
form spores. 

Glucose Agar-agar Stab. — Growth along the line of inocu- 
lation, with the production of a few gas-bubbles in the medium. 

Bouillon. — Clouded with the formation of a thin pellicle. 

Potato. — Thin, colorless, viscid layer. 

Litmus-milk. — Turned red and coagulated. 

Gelatin. — Growth not remarkable. 

There apparently exists a number of varieties of aerobic capsu- 
lated bacilli differing from one another only in non-essential par- 
ticulars. The organism here described is to be taken as a type of 
a group of closely-related bacteria of which the bacillus pneu- 
monia* of Friedlander is a well-known member. 



BACTERIOLOGICAL METHODS. 219 

Occurrence. — This organism or closely related forms may 
be met with in broncho- or lobular pneumonia and in inflam- 
matory conditions of the air-passages generally. It may 
also be present in the upper air-passages of healthy individ- 
uals. It has been observed in inflammations of the middle 
ear, in empyema, meningitis, endocarditis, peritonitis, and in 
pus-formations. In fatal infections the blood-stream may be 
found invaded by the organism. It is held by some bacteri- 
ologists that the members of this group may be the infective 
agents in genuine croupous pneumonia in rare instances. 
Representatives of this group have been found in the soil, 
in the air, and in contaminated water. 

Bacillus of Tetanus. 1 — This bacillus will not grow in 
the presence of oxygen. 




FIG. 89. — Tetanus bacilli showing flagella, from a preparation stained by Dr. 
Hugh Williams ; X 2000 (Wright and Brown). 

Morphology . — Slender rods with rounded ends, which may 
grow into long threads. In the incubator spores are rapidly 
formed. These are round, wider than the bacillus, and are 
situated at the end of the rod, giving the appearance of a 
drum-stick or a round-headed pin (Fig. 93). 

The colonies in anaerobic glucose-gelatin cultures appear 
after several days as small clumps of interlacing fibrillar from 

1 Kitasato : Zeitschrift f. Hygiene ti. Infections krankheiten y Bd. 7, 1SS9. 



220 



PA THOL GICA L TE CHNIQ UE. 



which delicate filaments radiate into the gelatin, which is 
slowly liquefied. 

The colonies in simple anaerobic glucose-agar plate cul- 
tures (see page 1 24) appear after twenty-four to forty-eight 
hours in the incubator, as groups and masses of long fila- 
ments radiating from a center (Fig. 92). 





.Jt 







Fig. 90. — Tetanus bacillus. Stab- 
culture in glucose-agar. In the upper 
layers of the medium the peculiar 
brownish coloration is shown. 



Fig. 91. — Bacillus of tetanus : six- 
days-old stab-culture in glucose-gelatin 
(Frankel and Pfeiffer). 



Pathogenesis. — Subcutaneous inoculation of mice at the 
root of the tail gives rise to tetanic symptoms in twenty- 
four hours, followed by death in two or three days. 

Guinea-pigs and rabbits are also susceptible to the infec- 
tion, the period of incubation in these animals being twenty- 
four to thirty hours in the former and two to three days in 
the latter animal, after subcutaneous inoculation. The symp- 
toms of tetanus appear first in the extremities nearest the 



BA CTERIOL O GICAL ME THODS. 



221 



point of inoculation. In mice the hind legs become rigidly 
extended backward. At the autopsy the bacillus is to be 
found only at the point of inoculation, and may be difficult 
or impossible to demonstrate there. 

Glucose-gelatin Stab. — Growth along the line of inocula- 
tion, beginning 2 or 3 cm. below the surface, with delicate 
filaments radiating laterally into the gelatin (Fig. 91). Liq- 
uefaction and gas-production occur. 

In deep-stab cultures in glucose-agar faintly alkaline to 
litmus (see Fig. 90) growth appears first all along the line of 
inoculation to within about 1 cm. of the surface after about 
twenty-four hours in the incubator. Later, lateral out- 
growths extend into the medium from all along the line of 







" 






J 






-V''- / .'/ ~ ' ' ■ 
■■(■'■'■ '■ 



Fig. 92. — Colony of tetanus bacilli in anaerobic glucose-agar plate ; low mag- 
nifying power (Wright and Brown). 



inoculation below a point about 1 cm. below the surface. 
In the portion of the line of inoculation above this, growth 
is frequently observed up to the surface, but without lateral 
outgrowths. The growth eventually assumes the appear- 
ance of an inverted pine tree. A peculiar feature of the 
culture is the appearance of a brown pigmentation in the 
culture-medium in its upper layers in the form of a flat or 
cone-shaped zone. A small quantity of gas may be pro- 
duced. 

If the agar has a reaction of about 1 per cent, normal 
acidity to phenolphthalein (see p. 84) growth appears 



222 PATHOLOGICAL TECHNIQUE. 

along the line of inoculation and spreads through the 
medium as a cloudiness extending to within a few millimeters 
of the surface. The employment of glucose culture-media 
not older than a week or so seems to be important for 
success in cultivating this organism. 

In the vegetative form the organism is sluggishly motile. 
It has numerous flagella. It is stained by Gram's method. 

Glucose-bouillon. — Growth appears first, after twenty-four 
to forty-eight hours, as a diffuse cloudiness. Later the 
fluid becomes clear, and a grayish sediment collects at the 
bottom of the tube. Only a small amount of gas is pro- 
duced. 

Occurrence. — Found in the soil, and often in the feces of 
herbivorous animals. In cases of tetanus the bacillus is to 
be found only in the wound or at the point of inoculation. 
It does not invade the blood-current. 

The bacillus of tetanus acts by the production of a " toxin " 
or " toxalbuminy This is also produced in cultures. It may 
be demonstrated in the bacteria-free filtrate of bouillon cult- 
ures some days or weeks old. A very few drops of this 
fluid will give rise to fatal tetanus in a mouse. 

Method of Isolation. — Tetanus bacilli will grow in aero- 
bic culture if other bacteria are growing with them. Since 
tetanus wounds usually contain other bacteria, all that is 
necessary to obtain an impure culture of the tetanus bacillus 
is to inoculate an ordinary blood-serum culture-tube (see 
page 79) with material from the wound. After several 
days or a week in the incubator, if tetanus bacilli are present 
they can be recognized by cover-glass preparations from 
the growth in the tube by their morphology and spore- 
formation (see Fig. 93). There will also be a peculiar, 
stinking odor about the culture. The isolation of the 
tetanus bacillus is now to be proceeded with as follows : 
Mix a loopful of the mixed growth on blood-serum with 
a tube of sterile bouillon, and heat in a water-bath for at 
least fifteen minutes at 8o° C, then make anaerobic cultures 
from this (see Anaerobic Methods, page 121), taking several 
loopfuls for inoculation. 



BACTERIOLOGICAL METHODS. 223 

If other spore-bearing- bacilli are present in the mixed 
culture in the blood-serum tube, it will be necessary to use 
some form of anaerobic culture on a solid medium in order 
to obtain separate colonies of the tetanus bacillus for further 
cultures. 

The bacillus may be isolated from wounds and from the 




FIG. 93. — Spore-bearing tetanus bacilli in an impure culture on blood-serum 
from a case of tetanus. In the bacillus on the extreme left the beginning of 
spore-formation is shown (Wright and Brown). 

soil by inoculation of mice subcutaneously, and proceeding 
as above described with material from the seat of inoculation. 

Bacillus Aerogenes Capsulatus. 1 — Will not grow in 
the presence of oxygen. 

Morphology. — Bacilli of about the thickness of the anthrax 
bacillus, variable in length, but usually 3 to 6/z long. Ends 
rounded or square cut. Occurs singly, in pairs, in clumps, 
and sometimes in short chains, less frequently in threads 
and long chains. 

May show unstained spots or deeply staining granules in 
the protoplasm. Capsules may be frequently demonstrated 
in the specimens from the tissues, and sometimes in agar- 
agar cultures. 

Colonies in anaerobic cultures are grayish to brownish- 
white, with a central darker spot by transmitted light. In 
time they may attain a diameter of 2 to 3 mm. or more. 
Colonies in the depths are spherical or oval, sometimes pre- 
senting knob-like or feathery projections. 

Effects 011 Animal Tissues. — Not pathogenic for rabbits. 

1 Welch and Flexner : Journal of Experim. Medicine^ vol. i. No. I, 1S00. 



224 PATHOLOGICAL TECHNIQUE. 

If a rabbit that has received 0.5 to 1 c.c. of a bouillon 
culture injected into the ear-vein be killed immediately after- 
ward and the body kept for twenty-four hours at a tempera- 
ture of 1 8° to 20 C, or for four to six hours at a tempera- 
ture of 30 to 35 C, the vessels and organs will be found 
to contain a great quantity of gas and large numbers of the 
bacilli. The organism multiplies post-mortem in the blood 
of the animal and produces the gas. This effect upon the 
tissues of the dead animal is characteristic of the bacillus. 

The subcutaneous inoculation of guinea-pigs with young 
cultures may produce fatal gas phlegmons. The hemor- 
rhagic fluid from the dead animal is virulent for other guinea- 
pigs, and may be virulent for rabbits. 

Gas-production is marked in agar-agar and gelatin cultures 
containing glucose. The gas produced burns with a blue 
flame and is odorless. 

Gelati?i is liquefied slowly and to a limited extent. 

Glucose BouillcHi. — Diffusely clouded at first, later becom- 
ing clearer, with an abundant whitish, more or less viscid 
sediment. 

Milk. — Coagulated, the clot being firm, retracted, and fur- 
rowed with the marks of gas-bubbles. 

Potato. — Growth thin, moist, and grayish-white, or it may 
not be visible. 

The bacillus is stained by Gram's method. It is not motile. 
Spore-formation has been observed by E. K. Dunham. 

The vitality of the organism depends upon the character 
of the culture-medium and the mode of cultivation. It sur- 
vives longer when cultivated by Buchner's method (see 
page 124) than when cultivated under hydrogen. Cul- 
tures on glucose media are shorter lived than those on 
plain media. 

Occurrence. — Occurs at autopsies in which gas-bubbles are 
present in the larger vessels, accompanied by the formation 
of numerous small cavities in the liver containing gas. It 
has been found also in emphysematous phlegmons, in puer- 
peral sepsis, in peritonitis, and in other conditions. 



BA CTERIOL O GICAL ME THODS. 



225 



Bacillus of Malignant Edema. 1 — This bacillus will 
not grow in the presence of oxygen. 

Morphology. — Rather large bacilli, sometimes growing into 
threads (Fig. 94), but occurring frequently in pairs, in which 
the proximal ends are square while the distal ends are 
rounded. Forms oval spores in the middle of the rod, 
which may give the rod a spindle or oval shape. 

The colonies in anaerobic glucose-gelatin cultures appear 
as spheres of cloudy liquefied gelatin marked by delicate 
radiating streaks. Gas-bubbles are formed in the mediurr, 
(Fig. 95)- 




Fig. 94- — Bacillus of malignant edema from the edema fluid of a guinea-pig 
inoculated with garden-earth ; X iooo (Frankel and Pfeiffer). 



In glucose-agar the colonies appear as hazy points made 
up of interlacing filaments and resembling very much the 
colonies of the tetanus bacillus. 

Pathogenesis. — Subcutaneous inoculation of mice, guinea- 
pigs, and rabbits is followed by death in from sixteen to 
forty-eight hours, depending upon the animal, mice being 
most susceptible. The typical lesions are extensive sub- 
cutaneous edema containing gas-bubbles and more or less 
blood, and enlargement of the spleen. The bacilli are found 

1 Liborius: Zeitschrift f. Hygiene u. Infectionskrankheiten, Bd. 1, 1886. 
15 



226 



PA THOL O GICAL TE CHNIQ UE. 



in the edema, in the viscera, and on the serous surfaces of 
the organs, but not in the blood of the heart if the exam- 
ination be made immediately after death, except sometimes 
in mice. The organism is not capable of multiplying in the 
living blood, owing to the presence of oxygen. In inoculat- 
ing subcutaneously a deep pocket should be made in the 
skin, and the material for inoculation introduced into the 
tissue as far away from the opening as possible. This is to 

prevent the access of too much 
oxygen to the organism. 

Slightly motile. Flagella may 
be demonstrated by special stain- 
ing methods. 

The bacilli in tissues are stained 
by Gram's method, but in cultures 
most of them are decolorized by 
it, probably because of rapid de- 
generative changes in them. 

Growth in anaerobic agar-agar 
and bouillon culture is good, but 
not characteristic. 

Occurrence. — Widely distributed 
in the soil and in putrefying sub- 
stances. Only a very few cases 
are on record of infection in man 
by this bacillus. 

In a paper by A. H. Gould * will 
be found the account of a case in 
the Massachusetts General Hos- 
pital, a review of the literature, 
and a more extensive description 
of the bacillus than is here given. 
Actinomyces. — The proper 
classification of the micro-organism known as actinomyces is 
somewhat uncertain. The published descriptions of various 
examples of it vary widely and have led to much confusion. 
It is probable that some of the micro-organisms cultivated 

1 " A Case of Malignant Edema," Annals of Surgery, October, 1 903. 




Fig. 95. — Bacillus of malig 
riant edema ; colonies growing 
in glucose-gelatin (Frankel and 
Pfeiffer). 



BACTERIOLOGICAL METHODS. 



227 



and described as actinomyces were not such, but were con- 
taminations or secondary invaders of the tissues. 

Probably the best opinion to-day considers actinomyces 
to belong to a group of micro-organisms which, on account 
of their branching, are regarded as more highly developed 
than are the bacteria, but which are not so highly organ- 
ized as are the moulds or hyphomycetes. The members 
of this group, of which a number are known, are named 
streptothrices. While there is some objection to this name, 
it seems to us to be satisfactory. 





FIG. 96. — Actinomyces granule crushed beneath a cover-glass, showing 
radial striations in the hyaline masses. Preparation not stained ; low mag- 
nifying power (Wright and Brown). 

The organism appears in the pus from subacute or chronic 
suppurative lesions of the disease actinomycosis, as grayish 
or yellowish granules, usually less than 1 mm. in diameter. 
Sometimes these granules are aggregated in groups of two 
or three, and thus appear as lobulated larger granules. 
They are friable, and when gently crushed beneath a cover- 
glass and observed under the microscope, they are seen to 
have been broken up into hyaline rounded masses, at the 
margins of which, on close inspection, fine radial striations 
or filaments or hyaline club-shaped bodies, all closely set 
together, may be seen (Figs. 96, 97). The club-shaped 



228 



PA THOL O GICA L TE CHNIQ UE. 



bodies are variable in size, and are composed of a hyaline, 
refringent substance. The appearance of radial striation in 
the granule, when observed with the microscope, due to the 
presence and radial arrangement of these hyaline bodies, 
gave rise to the name " ray-fungus " for this parasite. Not 
all of the granules have these " clubs." In the granules 
obtained from the lesions in man they are much less fre- 
quently observed than in those obtained from the lesions in 
cattle. 

If a cover-glass preparation be made by breaking up one 
of the granules and staining with Gram's method, there will 
usually be found, upon examination with an oil-immersion 
lens, isolated and matted filaments r many of which may be 




Fig. 97. — A portion of an actinomyces granule crushed beneath a cover- 
glass, showing the "clubs." The preparation not stained; moderately high 
magnifying power (Wright and Brown). 



seen to branch, in addition to longer and shorter fragments 
of filaments and fine detritus of the same (Fig. 98). The 
filaments are usually more or less wavy in their course, and 
are, as a rule, slightly thicker than the tubercle bacillus. 
Some of the filaments will be found to stain homogeneously ; 
others do not stain so deeply, and show numerous deeply 
staining points in their substance. If clubs are present in 
the granule, they also may be found scattered throughout 
the preparation. 

In sections of the tissues stained by Gram's method two 
chief forms of granules are found. In one of these forms 
the granule is seen to consist of filaments embedded in a 
hyaline substance, and usually arranged at the periphery 
in an indefinite radiate manner (Fig. 99). At the margin 



BA C TERIOL O GICA L ME THODS. 



229 



of the granule the filaments are usually much more numer- 
ous than in the central portions, where the hyaline material 
predominates. This hyaline material apparently consists 
of degenerate or dead filaments or their remains. The 
other form of granule seen in sections is distinguished by 
possessing at its margin a row of closely set radiating club- 
shaped bodies composed of hyaline substance which does 
not stain by Gram's method (Fig. 100). These are the 
" clubs " previously mentioned, and they may occupy more 
or less of the circumference of the granule. In certain 




Fig. 98. — Branching actinomyces filaments in a cover-glass preparation 
made from an actinomyces granule stained by Gram's method ; X iooo (Wright 
and Brown). 

instances a Gram-staining filament may be seen in the cen- 
tral portion of a club. The main mass of this form of 
granule is not essentially different from that of the first- 
mentioned form. The characteristics of both forms of 
granule may be found in some granules. 

The club-shaped bodies are to be regarded as products 
of degeneration of the marginal filaments. 

In some cases isolated or small groups of filaments may 
be found scattered among the pus-cells in the lesions. 

Cultures. — Actinomyces grows best in the incubator. On 



23O PATHOLOGICAL TECHNIQUE. 

the surface of slant tubes of blood-serum and agar-agar the 
organism grows in larger and smaller grayish-white, shining, 
elevated colonies. If the colonies are few in number, they 
may attain a diameter of several millimeters, with highly 
elevated, irregular central portions and thin, wavy, marginal 
portions. If the colonies are very numerous, they may be 
confluent, and form a grayish granular layer. Growth on 






M 



y 



dM^T* ■ ■'■■ ■ 6* 



Fig. 99. — Colony or granule of actinomyces in a section through a lesion, 
showing the Gram-stained filaments and hyaline material and also the pus-cells 
surrounding the colony (Wright and Brown). 

the surface takes place more rapidly, and with a develop- 
ment of more numerous colonies if the culture be kept 
under anaerobic conditions, the maximum of growth being 
obtained in about a week. 

In stab-cultures in sugar-agar the colonies appear as 
grayish granules along the line of inoculation. 

In bouillon the organism grows in the form of grayish- 
white, friable granules or clumps at the bottom of the tube. 



BA CTERIOL O GICAL ME THODS. 



231 



The maximum of growth is obtained in about four or five 
days under aerobic conditions. The culture-fluid is never 
clouded. 

The morphology of the organism in cultures is subject to 
considerable variation. 

In bouillon-cultures it grows in the form of longer or 
shorter filaments which sometimes may be seen to branch. 
Scattered along the filaments are sharply defined, deeply 
staining, oval or rounded areas occupying the whole diam- 







1 ft v 



X 



•« 









Fig. 100. — Colony or granule of actinomyces in a section through a lesion, 
showing the peripheral arrangement of the "clubs." In several instances the 
central stained filaments in the " clubs " are seen ; x 750 (Wright and Brown). 



eter of a filament. Clubs are never observed in cultures, but 
sometimes round or oval swellings may be seen at the ends 
of the filaments in the older cultures. 

In cover-glass preparations from cultures on solid media 
the organism appears as longer and shorter rods, often more 
or less fusiform or club-shaped, and as slightly wavy fila- 
ments of variable length, sometimes segmented 

Diagnosis. — The finding of the granules in suspected pus 
may be facilitated by spreading the pus on a slide. 



232 



PA THOL O GICA L TE CHNIQ UE. 



The identification of the organism is made certain only 
when the granules have been found to present the appear- 
ances described above after crushing under a cover-glass, 
and after cover-glass preparations made from them and 
stained by Gram's method show the branching filaments. 

Mycetoma (Madura Foot). — Mycetoma is a chronic 
inflammatory process, most commonly affecting the tissues 
of the foot, in which suppurative nodular swellings, sinus- 




>y . .%. ..IT,-., -,:-.- ■,;y.?j>V5'.ffl^ 



Fk;. ioi. — Mycetoma. Black granule in a section from the lesions. The 
black rounded central mass represents the brownish hyaline refringent substance 
in which the fungus elements are embedded. Giant cells and granulation-tissue 
are shown (Wright and Brown). 

formation, and enlargement and distortion of the parts are 
prominent features. The bones may become involved and 
undergo a rarefying osteitis. 

The affection is characterized by the presence in the dis- 
eased tissue and in the discharge from sinuses, of peculiar 
granules, usually not more than one millimeter in diameter, 
but sometimes larger. These granules in certain cases are 
of a black color, of irregular shape, and are hard and rather 
brittle. In general they resemble grains of gunpowder. In 
other cases the granules are whitish, grayish, or yellowish in 
color, and are of a soft or cheesy consistency. They have 



BA CTERIOL O GICAL ME THODS. 



233 



been compared to fish-roe in appearance. A very few cases 
are also recorded in which the granules were of a red color. 
There is no sfood evidence to show that more than one kind 
of granules are ever present in any one case of the disease. 




Fig. 102. — Mycetoma: fungus elements from a black granule after maceration; 
high magnifying power (Wright and Brown). 

On account of the fact that at least two very different 
kinds of granules are found associated with the lesions, two 










FIG. 103.— Mycetoma, showing the outgrowth of hyphae from one of the black 
granules after planting in fluid culture-medium (Wright and Brown). 



varieties or forms of the disease are recognized : the " mela- 
noid" or black variety, in which the granules are black, and 
the " ochroid " or pale variety, in which the granules are 
white to yellow in color. 



234 PATHOLOGICAL TECHNIQUE. 

The pale variety is probably actinomycosis of the part, 
the " melanoid " or black variety is clearly not actinomycosis, 
and the parasite belongs to the hyphomycetes, a very dif- 
ferent class of organisms from that to which actinomyces 
belongs. 

The disease occurs frequently in India and some other 
sub-tropical countries. It is extremely rare in temperate 
climates. 

Wright has studied a case of the black variety of the dis- 
ease, and upon the results of this study l the following descrip- 
tion of the parasite is based : 




FIG. 104. — Mycetoma, showing details of the structure of the hyphae developed 
from the black granules (Wright and Brown). 

The black granules, characteristic of this variety of the 
disease, consist of a hard, rather brittle, amorphous, brownish 
or black substance in which a fungus mycelium is embedded 
(Fig. 1 01). These fungus elements may be demonstrated by 
macerating the granules in a strong solution of alkali or 
sodium hyposulphite. This disintegrates the granule and dis- 
solves the brown embedding substance. The fungus ele- 
ments obtained from the granules by this maceration are 
shown in Fig. 102. 

1 Journal of Experim. Medicine, 1898, vol. iii. Nos. 4 and 5. 



BACTERIOLOGICAL METHODS. 235 

The organism grows on ordinary culture-media about as 
rapidly as do the ordinary moulds of the laboratory. 

From a granule planted in bouillon numerous hyphae 
grow out into the fluid and may form eventually a whitish 
powder-puff-ball-like structure with the granule in the center 
(Fig. 103). The hyphae grow very long, are septate, have in 
places vacuoles, and form branches (see Fig. 104); on the 
surface of agar-agar the growth appears as a meshwork of 
widely spreading filaments of a grayish color. 

On potato it forms a dense, widely spreading, coherent 
membrane of velvety surface. In its central portions it is 
of a pale-brown color, but at the periphery it is white. A 
marked feature is the appearance of small spherical droplets 
of coffee-colored fluid on the surface of the growth after a 
time. 

It must be quite clear from the foregoing that the organ- 
ism belongs to the moulds or hyphomycetes. 

The formation of reproductive organs, such as spore-bear- 
ing hyphae, was not observed. 

The results of animal inoculations were negative. 

Rabies (Hydrophobia).— The diagnosis of this disease 
from a pathological standpoint is usually made by the pro- 
duction of experimental rabies in a rabbit by intradural 
inoculation with material from the nervous system of the 
animal suspected to have died of it. The poison of the dis- 
ease is found in the brain, spinal cord, salivary glands, and 
pancreas. For purposes of inoculation a piece (1 or 2 c.c.) 
of the medulla or brain, preferably the former, is rubbed up 
in a sterilized mortar with about 10 c.c. of sterilized distilled 
water. The resulting fluid is filtered through absorbent 
cotton, and then through filter-paper, to remove tissue- 
shreds. Of the clear fluid thus obtained 4 or 5 drops are 
injected beneath the dura of a rabbit by means of a hypo- 
dermic syringe, the skull being trephined with a small tre- 
phine about 4 mm. in diameter. The most favorable. place 
for opening the skull is at a point in the median line just 
posterior to a line drawn through the middle of each eye. 

The symptoms of experimental rabies in the rabbit first 



236 PATHOLOGICAL TECHNIQUE. 

manifest themselves after two weeks, never earlier, but they 
may not appear until later, not even until two months have 
passed. The first symptom is a weakness of the hind legs, 
followed by paralysis. The paretic condition soon extends 
to the fore legs, dyspnea appears, and death usually occurs 
in about three days after the onset of the symptoms. Para- 
lytic symptoms developing before two weeks are not due to 
infection with rabies, but to some other cause ; for instance, 
infection with the pneumococcus or other bacteria which 
may be present in the material inoculated. 

During the course of the disease the animal never appears 
stupid, with dull eyes, as in other infections, but remains 
" conscious," so to speak, until the last. 

It is claimed that the diagnosis of rabies may be made by 
means of microscopical examination of sections of the me- 
dulla and spinal cord and of the peripheral ganglia of the 
cerebrospinal and sympathetic nervous system. The lesions 
in the medulla and spinal cord consist in the accumulation 
of round cells in the perivascular spaces and about nerve- 
cells and central canal, together with degeneration of nerye— 
cells. The lesions in the peripheral ganglia are rpofe im- 
portant and consist of degeneration of the ganglion-cells, 
together with a proliferation of the peculiar endothelial cells 
enveloping the ganglion-cells. The plexiform ganglia of the 
pneumogastric nerve are the best to examine. 

McCarthy and Ravenel x state that they know of no other 
acute disease in dogs presenting these lesions, and they con- 
sider them to be pathognomonic of rabies in an animal that 
had manifested the clinical symptoms of the disease. In 
order that these characteristic lesions may develop and 
permit of a diagnosis being made, it is necessary that the 
suspected animal be allowed to die of the disease or be 
killed in its advanced stages. 

1 Jour. Amer. Med. Assoc, March 21, 1903. 



PART III. 
HISTOLOGICAL METHODS. 



Introduction. — The ideal function of the technique of 
pathological histology is so to fix tissues for microscopic 
examination that every tissue-element or pathological prod- 
uct is perfectly preserved with all its morphological and 
chemical properties intact, and so to stain tissues that every 
tissue-element or pathological product can be readily differ- 
entiated from any other tissue-element or pathological prod- 
uct that resembles it. In certain respects only has this ideal 
yet been reached, but the number of differential stains is 
increasing yearly. 

In the following pages the various steps in the prepara- 
tion and staining of tissues have been arranged, so far as 
possible, in logical sequence. 

LABORATORY OUTFIT. 

Microscopes. — The most important laboratory instru- 
ment is the microscope. It should be, so far as means will 
permit, the best that skill can produce. Excellent micro- 
scopes are manufactured both abroad and in this country, 
but no make of microscope can be unconditionally recom- 
mended. Undoubtedly the best microscopes in every par- 
ticular and the most expensive are those manufactured by 
Zeiss. 

It is important for a beginner in microscopy, before buy- 
ing a microscope of any make, to have it carefully examined 
and its lenses tested at a pathological or other laboratory by 
some one skilled in its use. The continental form of stand 
of medium size is to be preferred to all others. The large 
stand is undesirable, because it is too heavy and too high for 

237 



238 PATHOLOGICAL TECHNIQUE. 

comfortable use. It should be furnished with rack and pin- 
ion, and with micrometer screw for coarse and fine adjust- 
ment, with a triple nose-piece, and with an Abbe condenser 
and iris diaphragm. The necessary objectives are a low and 
a high dry, and a -^ oil-immersion. Two eye-pieces, a low 
and a high, will be found sufficient for all ordinary purposes. 

The stands, oculars, and objectives of the Zeiss make 
generally used are the following : 

Stands, lla, Wa, IVb. 

Oculars, 2 and 4. 

Objectives, AA, D, and -^ oil-immersion. 

Or in the apochromatic series, 

Oculars, 4, 6, and 8. 

Objectives, 16.0, 8.0, 4.0, and oil-immersion 2.0 mm., 
apert. 1.30. 

Even if all these different parts cannot be purchased at 
the same time, it is important to buy a stand to which they 
afterward may be added, for the list includes only what every 
medical practitioner should have at his service for the proper 
examination of urine, sputum, blood, etc. 

The apochromatic lenses and compensation oculars are 
too expensive to come into general use. Fortunately, they 
are more important for photomicrography than for general 
microscopic work. 

The oil-immersion lens should always be cleaned after 
using by wiping off the oil with an old linen or silk hand- 
kerchief or with the fine tissue-paper now manufactured for 
that purpose. If the lens is sticky, moisten the cloth with 
benzol or xylol ; Leitz recommends alcohol. The same 
process can be used if necessary for the dry lenses, but it 
must be done quickly, so as not to soften the balsam in 
which the lenses are imbedded. Ordinarily a dry cloth is 
sufficient. 

In using the Abbe illuminating apparatus it is important 
to bear in mind that the best results are obtained, according 
to Zeiss, by employing the plain mirror, for the condenser is 
designed for parallel rays of light. The concave mirror is 
to be used only when some near object, such as the window- 



HISTOLOGICAL METHODS. 239 

frame, is reflected into the field of vision or when artificial 
light is employed. 

A mechanical stage is now made which can be instantly 
attached to any microscope. It is exceedingly useful for 
blood-counting or for searching carefully the whole surface 
of a stained cover-slip. For ordinary work it is undesirable. 

For microscopic work the best illumination is that obtained 
from a white cloud, although for some purposes the light 
which filters through a white curtain on which the sun is 
shining is very useful, especially with the highest powers of 
the microscope. When artificial light is necessary, the 
Welsbach burner, or, better still, the Edison electric lamp 
with ground-glass globe, will be found very satisfactory. 
The slight yellowish tint of the light can be corrected, if 
necessary, by means of a piece of blue glass inserted over 
the mirror or just below the object to be examined. 

For drawing, the Abbe camera lucida will be found ex- 
tremely useful and convenient. 

Freezing Microtome. — Freezing by means of the 
evaporation of ether, more rarely of rhigolene, is the 
method in general use. The process is both expensive 
and slow. A much cheaper and more rapid method of 
freezing was originated several years ago in the Sears Patho- 
logical Laboratory by Dr. S. J. Mixter, and has since been 
in constant use both here and in the hospitals in Boston. 
This method consists in the employment of compressed 
carbon-dioxid, which is found in commerce in iron cylinders 
containing each about twenty pounds of liquefied gas. It is 
commonly used for charging beer and soda-water. As a 
rule, the cylinders are loaned, so that it is necessary to pay 
for the contents only. 

The cylinder must be securely fastened in an upright 
position near the microtome, with its valve end below and 
with its escape-tube on a level with the entrance-tube into 
the freezing-box. The cap covering the escape-tube of the 
cylinder should have a small hole bored through it, and into 
this hole a small brass tube about 5 cm. long, with a fine 
bore, should be tightly driven. This permits the use of a 



240 PATHOLOGICAL TECHNIQUE. 

smaller stream of gas than the escape-pipe of the cylinder 
would otherwise furnish. The same cap can be kept to use 
on all future cylinders. 

The cylinder is connected with the microtome by means 
of a short piece of thick, strong rubber-tubing with small 
bore, so as to fit snugly over the escape-tube of the cylinder 



FIG. 105. — Freezing microtome. 

and the entrance-tube into the freezing-box. It is advisable 
to wire each end of the rubber-tubing around the tube it 
incloses. 

In order to obtain better leverage and more perfect con- 
trol over the escape of the gas than are needed for the 
purposes for which the cylinders are ordinarily used, it is 
necessary to lengthen to about 25 cm., in whatever way 



HISTOLOGICAL METHODS. 24 1 

seems best, the handle of the key which opens the escape- 
valve. 

The first time the cylinder is used for freezing", a little 
water may escape, causing considerable sputtering. In 
freezing, the valve should be turned carefully, so that the gas 
may escape slowly and evenly. Tissues fixed by alcohol or 
any other reagent, except formaldehyde, must be washed in 
running water for some hours before they can be frozen. 

The freezing-box of the microtome should be stronger 
than when intended for the use of ether. The Bausch and 
Lomb table microtome, No. 3050, with freezing attachment 
No. 3082, is recommended. 

For cutting frozen sections the blade of a carpenter's 
plane, 2-| inches wide, mounted in a wooden handle (Fig. 
106), will be found very serviceable and easy to sharpen. 




FIG. 106. — Knife for freezing microtome, made from the blade of a carpenter's 

plane. 

Directions for Cutting" Frozen Sections. — Sections of 10 
or 15 microns in thickness or as thin as good celloidin sec- 
tions, are readily obtained with most material by following 
these directions. 

The knife must be sharp and free from nicks. It must 
have a chisel edge, as shown in Fig;. 106. It should be 
sharpened by grinding on a hone, and afterward by thor- 
oughly stropping on a razor-strop. Frequent stropping is 
just as necessary as in the case of the ordinary microtome 
knife. 

In cutting, grasp the knife by the thick wooden handle so 
that the end presses against the ball of the thumb and the 
palm of the hand, while the dorsum of the hand is upper- 
most ; then, with the wrist flexed and held against the chest, 
apply the edge of the knife to the glass ways of the micro- 
tome in such a manner that the edge, bevel side downward, 
ifi 



242 PATHOLOGICAL TECHNIQUE. 

is at right angles to the direction of the ways and the long 
axis of the knife at an angle of 45 degrees to their surface ; 
now, holding the knife and wrist rigidly in the positions just 
indicated, push the cutting-edge quickly forward along the 
ways through the specimen by moving the body forward 
from the waist, in the mean while pressing the cutting-edge 
steadily downward upon the ways with constant force. Thus 
a strong constant downward pressure of the edge upon the 
ways is maintained, and at the same time great steadiness 
and power are given to the cutting stroke, which are condi- 
tions that are very important for obtaining thin sections. 
With the fingers of the other hand manipulating the wheel 
of the microtome screw, a number of sections should be cut 
in quick succession in the manner indicated without chang- 
ing the angle of the knife or the position of the hand and 
wrist above described, the edge of the knife on the back- 
ward movement being lifted from the ways only enough to 
clear the cut surface of the specimen. The sections will 
usually adhere to the knife, and a number of them may be 
allowed to collect thereon. They are removed from the 
knife by immersing it in water, in which they will float and 
flatten out, no matter how much wrinkled and compressed 
upon the knife they have been. The cutting of a number 
of sections in quick succession without pausing to remove 
each section from the knife seems to be necessary for obtain- 
ing the thinnest sections. 

The consistence of the frozen tissue is important. The 
specimen immediately after freezing will usually be too hard 
to cut without yielding sections that break over the edge of 
the knife, and are, therefore, to be rejected. If this happens, 
wait a few seconds and thereafter cut a section or two at 
short intervals until the specimen is found to have a con- 
sistence yielding satisfactory sections, whereupon a number 
of sections should be cut in quick succession as above de- 
scribed. The piece of tissue from which the sections are to 
be cut should not be thicker than 5 mm. 

Celloidin Microtome. — There are two types of celloidin 
microtomes — one in which the object is raised by a screw, 



HISTOLOGICAL METHODS. 



243 



a second in which the object is raised by being moved up an 
inclined plane. The first type of machine is the better, for 
two reasons : the screw affords greater accuracy in the even 
elevation of the object than is possible with an inclined 




FlG. 107. — Large laboratory microtome. 



plane, and the object remains at all times in the same rela- 
tive position with regard to the knife, so that an equally long 
sweep of the blade can be obtained for every section. An 
excellent instrument of this type is made by Bausch & Lomb 
(Fig. 107). For practical work it is much to be preferred to 
the elaborate Schiefferdecker-Becker microtome, designed 
for cutting sections under alcohol. 

A new and wholly original microtome, in which the knife 
remains fixed and is clamped at both ends, while the object- 
holder, which is raised by a screw, moves back and forth be- 
neath the knife, has recently been designed by Dr. C. S. Minot 
and is manufactured by Bausch & Lomb (Fig. 108). It is 
intended both for celloidin and for paraffin work. When but 
one instrument can be afforded, it is believed that this model 
will be found the most serviceable for both kinds of work. 

A drop-bottle on an elevated stand, with screw arrange- 
ment for regulating the amount of alcohol, is the most con- 



244 



PATHOLOGICAL TECHNIQUE. 



venient method for keeping the object and the knife wet 
while cutting ; 80 per cent, alcohol should be used. 




The Minot-Blake Microtome. 1 — This microtome is 
specially designed for cutting sections of I and 2 micra in 
thickness, but it may be adjusted to cut sections up to 10 
micra. The main sliding parts are designed to take advan- 

1 This microtome is made by the Buff Manufacturing Co., 506 Atlantic 
Ave., Boston, Mass. 



HIS TOLO GICA L ME THODS. 



245 



tage of the principle of three-point bearings, so as to avoid 
minute irregularities in their motions. The knife is provided 
with a brace to prevent the elasticity of the knife-edge from 
causing "skipping" when the machine is adjusted to 1 or 2 
micra. 




Fig. 109. — Minot-Blake microtome. 

In operating this machine for thin sections the following 
important points should be borne in mind : 

1. The machine must be in accurate adjustment. The 
brace to the knife is to be so applied as not to produce a 
twisting strain upon it. The upper edge of the brace should 
lie about ■£§ of an inch below the knife-edge. The knife is 
to be canted just enough to obtain clearance, and no more. 



246 



PA THOL O GICA L TE CHNIQ UE. 



2. The knife-edge should be so well polished that, when 
observed with the microscope under a magnifying power of 
about 90 diameters, it appears as a straight line. 

3. The specimen must be well embedded, and the paraffin 
block containing it, as well as the brass carrier to which it 
is attached, should be cooled in ice-water immediately before 
cutting. The knife and its brace should be likewise cooled. 
The paraffin block is to be carefully trimmed as described 
elsewhere. 

Paraffin Microtome. — Although paraffin sections can 
be cut on a celloidin microtome, it is preferable to have an 




Fig. iio. — Minot wheel microtome. 

instrument designed for the purpose. The Minot wheel 
microtome manufactured by Bausch & Lomb (Fig. no) can 
be thoroughly recommended. 

Paraffin Bath. — The best bath for keeping paraffin at a 
constant temperature is a thermostat of suitable size with 
hot-water jacket, such as is used for growing cultures of 
bacteria. The paraffin is kept in it on shelves in glass dishes 



HIS TOL O G/CAL ME THODS. 



247 



of various sizes. The advantages of this method over the 
old way of using copper cups set into the top of a water- 
bath are that the paraffin is kept absolutely free from dust, 
each worker can have his own set of dishes, and the smallest 
bits of tissue can be readily found in them, because they are 
transparent. 

A paraffin melting at 50 to 5 2° C. will be found convenient 
for use throughout the year if the laboratory is kept fairly 
warm in winter. Many workers, however, prefer one par- 
affin melting at 45 ° C. for winter, and another melting at 
48 C. for summer. 

A preliminary bath of soft paraffin is wholly unneces- 
sary, and only prolongs the objectionable stage of heating. 
The regulator should register only one or two degrees above 
the melting-point of the paraffin. 

Paraffin should be melted and decanted or filtered before 
use, as it often contains foreign material. When hot it runs 
through an ordinary filter without trouble. A hot-water 
jacket to the funnel is not at all necessary. 

Vulcanised Fiber.— For mounting celloidin prepara- 
tions nothing is so poor as cork, although it has been in use 
for years. The chief objections to it are that it does not fur- 
nish a rigid support to the imbedded object; that, unless 
weighted, it floats in alcohol with the specimen downward ; 
and that it yields a coloring material which stains both the 




Blocks of vulcanized fiber. 



alcohol and the specimen. Wood is not much better, 
although, of course, much firmer. Glass blocks have been 
proposed, and might do fairly well if there did not exist an 
ideal substance — viz. vulcanized fiber. This can be obtained 
in boards or strips, preferably \ or 4 inch in thickness and 



2AS 



PA THOL O GICA L TE CHNIQ I '£. 



sawn to any desired dimensions. It is perfectly rigid, is 
heavy enough to sink specimens to the bottom of the jar in 
an upright position, is unaffected by alcohol or water, is light 
red in color, so that it is easily written on with a lead pencil, 
gives off no coloring material, and is practically indestructible. 
Two or three parallel cuts, i to 2 mm. in depth, should 




Fig. 112. — Diagram of the direction of the movements in honing. 

be sawn into the upper surface of each block, so as to give 
the celloidin a firm hold. 

Knives. — The knives for both the celloidin and the 
paraffin microtomes should be heavy and not too long, so as 







Fig. 113. — Diagram of the direction of the movements in stropping. 

to afford as great rigidity as possible; they should be bicon- 
cave, so that they may be easily sharpened. It is important 
that ever}' one who does much work in a pathological labor- 
atory should learn to sharpen his own knives. The requisite 



HIS TO I O GICA I ME THODS. 



249 



skill is not difficult to acquire, and the time spent in learning 
is fully compensated for by the ability always to have a sharp 
knife when it is wanted. For honing a knife either a fine 
water-stone or a glass plate with diamantine and Vienna 
chalk may be used. In honing, the edge of the knife is for- 
ward and the motion is from heel to toe. The knife should 
always be turned on its back, and the pressure on it should 
be at all times rather light. 

In stropping, the movement is reversed. The back of the 
knife necessarily precedes the edge, and the motion is from 
toe to heel. The direction of the movements in honing and 
stropping is best illustrated by the diagrams (Figs. 112, 113). 

Running" water for washing out specimens which have 
been fixed in Flemming and other solutions is most easily 




Fig. 114. — Large laboratory sink, showing adjoining shelf and arrangement for 

running water. 



supplied by having a water-pipe, furnished with numerous 
cocks 5-10 cm. apart, run horizontally over a slightly slop- 
ing shelf adjoining the sink. Attached to each cock is a 
rubber tube, with a glass tube in the end of it long enough 
to reach to the bottom of the jar (Fig. 114). By this arrange- 



250 PATHOLOGICAL TECHNIQUE. 

ment the amount of water supplied to each specimen can be 
easily regulated. 

Slides should be of colorless glass with ground edges. 
The English form, measuring 1 X 3 inches (76 X 26 mm.), is 
to be preferred for ordinary use. Occasionally broader slides 
are needed. Thick slides are preferable to thin ones; the 
latter are so light that they are easily lifted by the oil- 
immersion lens ; they also seem to warp when heated to 
attach paraffin sections to them. 

Cover-slipS should be square or oblong according to the 
shape of the specimen. Most dry lenses are adjusted for 
cover-glasses measuring 16 or ij/i in thickness, so that if 
possible no cover-slips ranging outside of 15 to 18/i should 
be used. With an oil-immersion the exact thickness is not 
quite so important. 

Slides and cover-slips are cleaned by dipping in alcohol 
and wiping dry with a soft crash towel or old linen handker- 
chief. 

To clean old slide preparations, heat them until the bal- 
sam softens so that cover-slips and slides can be drawn 
apart. The slides and cover-slips are then treated separately 
with nitric acid. A 10 per cent, solution is usually sufficient, 
but occasionally the strong acid will be found necessary. 
Some workers prefer equal parts of alcohol and hydrochloric 
acid ; still others the following mixture : 

Bichromate of potassium, 2 parts ; 

Sulphuric acid, 3 " 

Water, 25 " 

A thorough washing in running water, followed by alco- 
hol, completes the process. Alkalies are not so good for 
cleaning purposes, because they attack the glass. 

Staining Dishes. — Watch-glasses are not satisfactory 
on account of their instability. Concave dishes with flat 
bottoms are much better for ordinary use, and can be ob- 
tained of several patterns. They should be large enough 
to hold 25 c.c. of fluid. The Syracuse solid watch-glasses 
are very good dishes of this shape. 



HIS TO 10 GICA I ME THODS. 



251 



Stender dishes of various sizes will be found useful for 
many purposes. 

The "New Practical Staining Dish" (No. 16,618) manu- 
factured by the Bausch and Lomb Optical Co. is very useful 
for staining at once a number of paraffin sections. 





FlG. 115. — New practical staining dish. 

Oblong rectangular Petri dishes are very convenient for 
staining preparations mounted on the slide. 

For staining at once a large number of sections for class 
purposes, the HobUs Tea Infuser has been found very useful. 
If set in a small lemonade cup, but little stain is required. 

Large concave dishes holding 1000 c.c. will be found the 
most convenient for holding frozen sections of fresh tissue, 
because a slide can be dipped into them and under the 
sections. 

Metal Instruments. — Spatulas of different sizes are 




FlG. 116.— Spatula. 



needed. They should be thin, smooth, and large enough, 
so that a section will not curl over the edge (Fig. 1 16). 
The best instrument for transferring sections under all cir- 



252 PATHOLOGICAL TECHNIQUE. 

cumstances is a piece of platinum wire mounted in an ordi- 
nary screw needle-holder. It is pliable and can be bent to 
any shape, will not break like a glass needle when dropped, 
and is not affected by acids. Ladies' hat-pins form a cheap 
but serviceable substitute. They are readily bent to any 
desired shape by heating. Forceps, scissors, scalpels, and 
many other instruments required in microscopical work do 
not need any special mention. 

Bottles. — For cover-slip work and for staining on the 
slide dropping-bottles will be found extremely convenient. 
The patent T. K. pattern of 50 c.c. capacity, with flat top, is 
probably the best form and size. 



EXAMINATION OF FRESH MATERIAL. 

Fresh tissues may be examined either in teased prepara- 
tions or in sections. 

Teased preparations are made by cutting out a very small 
bit of the tissue in question and dividing it as finely as pos- 
sible, by means of two sharp, clean needles, on a slide in a 
drop or two of some indifferent fluid, such as the normal 
salt solution. Teased preparations are often made, for in- 
stance, of the heart-muscle when fatty degeneration is sus- 
pected. If the tissue is soft, the cells are easily obtained 
by simply scraping the cut surface with the edge of the 
knife. 

Sections of fresh tissues can be made with a razor or with 
a double knife, but much the better way, atjeast for general 
diagnostic purposes, is to use frozen sections, which can be 
very quickly and perfectly made with the freezing microtome. 
The fresh sections are put into salt solution in a glass dish 
large enough to permit of a slide being dipped into it, so 
that a section can be floated and spread out evenly on its 
surface. The slide is then carefully raised, the excess of 
fluid wiped off, and a cover-slip put on. 

If it is desired to stain the section, a few drops of Loffler's 
methylene-blue solution are poured over it after it is spread 



HISTOLOGICAL METHODS. 253 

evenly on the slide. In a few seconds the coloring fluid is 
thoroughly washed off with salt solution, a cover-slip put on, 
and the section examined in the salt solution. If sections of 
fresh tissues are put directly into a staining fluid in the ordi- 
nary manner, they pucker up and do not stain evenly. 

Sections of fresh tissue may be fixed, stained, cleared, and 
mounted in balsam by a slight modification of the method 
for frozen sections given on p. 263. This modification con- 
sists in covering the section with 95 per cent, or absolute 
alcohol after it has been spread out evenly on the slide as 
described in the method referred to. The alcohol is to be 
dropped on the section carefully from a drop bottle, in order 
to avoid folding. After thirty seconds the alcohol is drained 
off and the section flattened out on the slide with blotting- 
paper and further treated according to the method above 
mentioned. If the section is not treated with alcohol before 
blotting, it will adhere to the blotting-paper and riot to the 
slide. 

Fresh preparations are often treated with chemicals for 
various purposes. Of these chemicals, acetic acid is the 
most generally useful in pathological work. It shrinks the 
nuclei and renders their outlines more distinct. It swells 
connective tissue, making it more transparent, so that the 
elastic fibers which are unaffected stand out distinctly. It 
precipitates mucin and dissolves or renders invisible the 
albuminous granules so abundantly present in the proto- 
plasm in the cloudy swelling of various organs in disease. 
Its main use as a reagent for fresh tissues is to demonstrate 
fat and to differentiate that substance from albuminous gran- 
ules. 

Acetic acid is ordinarily used in a 1 to 2 per cent, aqueous 
solution, a few drops of which are placed at one edge of the 
cover-slip, and then drawn beneath it by placing a piece of 
filter-paper on the opposite side. If in a hurry, however, 
stronger solutions, or even glacial acetic acid, may be used. 
Other reagents are of less importance, but are occasionally 
used. 

Osmic acid is sometimes employed in a 1 per cent, aque- 



254 PATHOLOGICAL TECHNIQUE. 

ous solution to demonstrate fat, which it stains brown to 
black. 

An alcoholic solution of Scharlach R. or Sudan III. is 
being used more and more for the same purpose. It stains 
fat orange to red. 

Hydrochloric acid in a 3 to 5 per cent, solution is used to 
demonstrate calcification. Phosphate of lime is simply dis- 
solved, while from carbonate of lime bubbles of carbon- 
dioxid (C0 2 ) are set free. 

Indifferent Fluids. — Fresh tissues are usually examined 
in normal salt solution — a T 6 ^ per cent, solution of common 
salt in water. It has the advantage over water that tissues 
do not swell up so much in it, blood-globules are unaffected, 
and the finer structures are better preserved. A very few 
drops of Lugol's solution added to the stock-bottle of 
salt solution will be found useful in preventing the growth 
of mould. / 

Serous fluids, such as hydrocele fluid, are occasionally 
used. Artificial serum is made by adding 1 part of egg- 
albumin to 9 parts of normal salt solution. 

Macerating fluids are little used in pathology. Occa- 
sionally, however, when tissues are tough, so that they cannot 
be readily teased apart, they are macerated in certain fluids 
which dissolve the substances that hold the different ele- 
ments together. The reagents most commonly used are the 
following : 

1 . Ranvier's one-third alcohol is made by taking 1 part of 
96 per cent, alcohol and 2 parts of water ; twenty-four hours 
are usually enough. 

2. Very dilute solutions of chrotnic acid are recommended 

— TFO to 3W ofl P er cent - 

3. jj per cent. Caustic Potash. — Tissues are macerated in 

a few minutes to one hour : they must be examined in the 
same fluid, because the cells are destroyed if the solution is 
weakened. 

Examination of Fluids. — Small fragments of tissue 
should be picked out with forceps. If much blood is ad- 
herent, wash the tissue well in salt solution. When the cell- 



HISTOLOGICAL METHODS. 255 

ular elements are few in number, they are obtained with a 
pipette, just as in urine-work, after allowing them to settle 
at the bottom of the glass. A centrifugal machine will be 
found of great service when the sediment is slight. 



INJECTIONS. 



Injections are not much used in pathology. The process 
is an art that requires much patience and considerable ex- 
perience. The purpose of an injection is to render vessels 
and vessel-walls more visible than under ordinary circum- 
stances. Transparent, deeply colored fluid mixtures are 
used, which will become hard in the vessels. Some injec- 
tion-masses are employed cold, others warm. The warm 
injection-masses contain gelatin, and are much more trouble- 
some to use, but give much the more perfect results. For 
coloring the mass carmine is the best material, because it is 
a permanent color. 

The instruments required are cannulas of various sizes and 
a syringe, or, better still, a constant-pressure apparatus. 

When a warm injection-mass is used, the bottle containing 
the mass must be placed in a water-bath and kept at a tem- 
perature of about 45 C. The organ or animal to be in- 
jected must likewise be placed in a water-bath of the same 
temperature. 

It is very important that in connecting the end of the tube 
carrying the injection-mass with the cannula inserted in the 
vessel no air-bubbles shall enter. When blood-vessels are 
to be injected, it is advisable to wash them out first with 
normal salt solution. 

Cold Injection-masses. — i. Bine Coloring Mass. 

Soluble Berlin blue, I ; 

Distilled water, 20. 

2. Carmine Injcction-niass (Kollmann). — Dissolve 1 gram 
of carmine in 1 c.c. of strong ammonia plus a little water ; 



256 PATHOLOGICAL TECHNIQUE. 

dilute with 20 c.c. of glycerin. To this solution add 1 gram 
of common salt (NaCl) dissolved in 30 c.c. of glycerin. To 
the whole solution add an equal quantity of water. 

Fischer has obtained good results by washing out the vessels in 
the usual way with physiological salt solution, or, better still, with 
a fibrin-dissolving fluid such as a freshly filtered 8 per cent, solution 
of nitrate or sulphate of sodium and then injecting good fresh 
milk. Fix the tissues for at least twenty-four hours in a 10 per 
cent, solution of formalin plus 2 per cent, of acetic acid. 

Cut frozen sections and stain with Scharlach R. Counterstain 
in alum-hematoxylin. Mount in glycerin. The fat can also be 
stained with osmium tetraoxid. The capillaries are outlined by 
the fat emulsion stained red or black. 

Warm Injection-masses. — 1. Berlin Blue. — Warm the 
solution of Berlin blue given above, and add it, with con- 
tinual stirring, to an equal quantity of a warm, concentrated 
solution of gelatin prepared as follows : Allow clean sheets 
of the best French gelatin to swell up for one to two hours 
at room-temperature in double the quantity of water. Then 
dissolve them by warming gently over a water-bath. Filter 
the combined solution through flannel. 

2. Carmine-gelatin Mass. — This is by all means the best 
injection-mass to use, because it is permanent, but it is very 
difficult to prepare. 

Dissolve 2 to 2.5 grams of best carmine in about 15 c.c. 
of water, to which just enough ammonia is added, drop by 
drop, to effect the solution. Filter the fluid obtained, and 
add it, with continual stirring, to a filtered warm, concen- 
trated solution of gelatin (prepared as above) over the water- 
bath. Then add acetic acid slowly until the color changes 
to a bright-red shade. The exact amount desired is when 
the solution loses its ammoniacal odor and has a peculiar 
sweetish aroma free from acid. Examined, under the micro- 
scope, no granular precipitate of carmine should appear. If 
too much acetic acid has been added, so that the carmine is 
precipitated, the mass must be thrown away and a new lot 
prepared. 

Organs which have been injected with a cold mass are 
placed directly in 80 per cent, alcohol. After a few hours 



HISTOLOGICAL METHODS. 257 

they are to be cut up into pieces that are not too small. 
After a warm injection-mass the organ or animal is placed 
first in cold water to hasten the solidification of the gelatin, 
and then transferred to 80 per cent, alcohol. Masses already 
prepared for injecting cold or warm can be obtained from 
Gruebler. 



FIXING REAGENTS. 

The various reagents used for the preservation of fresh 
tissues possess the properties of penetrating, killing, fixing, 
hardening, and preserving in different degrees. Of these 
properties "fixing" is the most important, and to a certain 
extent implies or includes the others. The term " fixative " 
has been used more particularly, perhaps, for reagents which 
preserve faithfully the various changes of the nucleus in 
karyomitosis. In a broader sense, however, it refers to the 
faithful preservation of any tissue-element or pathological 
product, and of the chemical properties peculiar to that ele- 
ment or product. A good fixative is a reagent that pene- 
trates and kills tissues quickly, preserves the tissue-elements, 
and particularly the nuclei, faithfully in the condition in 
which they are at the moment when the reagent acts on 
them, and hardens or so affects them that they will not be 
altered by the various after-steps of staining, clearing, and 
mounting. Most fixatives are mixtures of different reagents 
so combined that all the desirable properties may be present 
in as large a degree as possible. 

The choice of the proper fixing reagent for a given tissue 
is often difficult, and must depend largely on the nature of 
the pathological lesions present or suspected, and on the 
purposes for which the tissue is preserved. For diag- 
nosis, for general bacteriological study of tissues, and for 
many valuable and important chemical reactions alcohol 
is to be preferred to any other reagent. Although by 
no means an ideal fixative, it will be found exceedingly 
useful. 

For finer histological study it is important to preserve 
17 



258 PATHOLOGICAL TECHNIQUE. 

valuable tissue in some more perfect fixative than alcohol. 
Zenker's and to some extent Orth's fluid will be found the 
most generally useful. Flemming's solution is especially to 
be recommended for the study of renal lesions with fatty 
degeneration. For general pathological work, aside from 
the nervous system, these four fixatives will be found the 
most valuable. 

It is strongly advised that in all important cases pieces of 
tissue be hardened both in alcohol and in Zenker's fluid — 
in alcohol for bacteria and for chemical reactions ; in the 
other for bacteria, nuclear figures, blood, and general histo- 
logical study. For special investigations other fixatives are 
sometimes desirable. 

Tissues fixed in alcohol or in a solution of formaldehyde 
may remain as long as desirable in those fluids. Tissues 
hardened in most of the other fixatives mjust be transferred, 
after thorough washing in water, to alcohol for preservation. 
It is usually recommended to pass the specimens through 
graded alcohols, either through 30, 60, 90, and 96 per 
cent., or through 50, 70, and 96 per cent., allowing them to 
remain from a few hours to a day in each strength. For 
most purposes it will be found sufficient to transfer the 
specimens directly from water to alcohol of 70 to 80 per 
cent., in which they may remain until it is desired to imbed 
them. 

Alcohol extracts chrome salts from tissues hardened in 
solutions of them. As these salts are precipitated in the 
alcohol under the action of light, it is desirable, although 
by no means necessary, to keep all such specimens in the 
dark. 

Alcohol. — The strength of alcohol ordinarily used in 
laboratories is 95-96 per cent. Absolute alcohol is much 
more expensive. Tissues hardened in either of these 
strengths shrink a great deal. The exposed surface be- 
comes extremely hard, and the outer layers of the cells of 
tissues, like a rabbit's kidney, for example, are as shrunken 
and flattened as though dried in the air. It is only inside of 
this hard casing, where the alcohol has penetrated more 



HISTOLOGICAL METHODS. 259 

slowly and has been somewhat diluted by the fluid of the 
tissue, that the cells are better preserved. Moreover, this 
extreme hardening of the surface hinders the penetration of 
the alcohol into the deeper parts. 

Tissue which is to be hardened in absolute or 95 per cent, 
alcohol should be cut into thin pieces, preferably not over 
\ cm. thick. The volume of alcohol used for hardening 
should be fifteen to twenty times as great as the specimen, 
and should be changed after three or four hours. The tissue 
should be kept in the upper part of the alcohol by means 
of absorbent cotton, or the jar may be frequently inverted 
and the alcohol thus kept of even strength. 

The advantages of strong alcohol, 95 per cent, and abso- 
lute, are that the tissue is more quickly fixed than with 
weaker strength, and that at the same time it is made quite 
hard — a quality more necessary formerly than now when tis- 
sues are so generally embedded. Tissues hardened in strong 
alcohol should later be transferred to 80 per cent, alcohol for 
preservation, or the staining properties will gradually become 
impaired. 

For general purposes it will be found better to place tissues 
at first into 80 per cent, alcohol, which should be replaced 
in two to four hours by 95 per cent, alcohol. In this way 
less shrinkage is caused and the surface of the tissues is not 
made so hard. 

Tissues which have been fixed in Zenker's and other fluids 
should, after thorough washing in running water, be placed 
directly in 80 per cent, alcohol for further preservation. 
Change the alcohol occasionally as it becomes cloudy. 

Zenker's Fluid. — 

Bichromate of potassium, 2.5 grams; 

Sulphate of sodium, 1 gram ; 

Corrosive sublimate, 5 grams ; 

Glacial acetic acid, 5 c.c. ; 

Water, ad 100 

Dissolve the corrosive sublimate and the bichromate of 
potassium in the water with the aid of heat. 



26o PATHOLOGICAL TECHNIQUE. 

The solution is practically Midler's fluid saturated with 
corrosive sublimate, plus 5 per cent, of glacial acetic acid. 
It is advisable not to add the acetic acid to the stock solu- 
tion, but only in the proper proportion to the part taken for 
hardening pieces of tissue, because the acid evaporates so 
readily. 

Directions for Use. — 1. Fix tissues in the solution twelve 
to twenty-four hours, rarely forty-eight hours, according to 
thickness. 

2. Wash in running water twelve to twenty-four hours. 

3. Preserve in 80 per cent, alcohol until used. 

Tissues float at first in this solution, which will be found 
a most admirable general fixative. It penetrates quickly, so 
that pieces of tissue do not need to be so thin as with most 
other fixatives, but it is advisable not to let them exceed 4 
to 6 mm. in thickness. Nuclear figures, red blood-globules, 
and protoplasm are all perfectly preserved. The greatest 
drawback to the fluid is the precipitation of mercury, which 
takes place to a varying degree in the tissues. This pre- 
cipitation can be removed by means of iodin, which forms 
a colorless, soluble compound. For this purpose it has 
usually been advised to add iodin to the alcohol in which 
the tissues are preserved. Prolonged treatment, however, 
is required, and iodin exerts an injurious effect on the stain- 
ing properties of the cells, so that in general it will be found 
best to embed the tissues and cut sections without removing 
the precipitate, and to treat the sections, just before staining, 
with Lugol's solution or a 1 per cent, alcoholic solution of 
iodin for ten to twenty minutes, followed by alcohol to 
remove the iodin. In old Zenker preparations the areas in 
the tissues occupied by the mercuric precipitate often stain 
with alum-hematoxylin, although the precipitate itself has 
been removed. 

Zenker preparations stain slowly but beautifully in alum- 
hematoxylin. Excellent results can also be obtained with 
eosin, followed by Unna's alkaline methylene-blue solution. 
Fuchsin and safranin stains are sometimes useful. 

Corrosive Sublimate. — Use a saturated solution (made 



HISTOLOGICAL METHODS. 26 1 

by heat) in normal salt solution. The addition of 5 per cent, 
of glacial acetic acid is usually advisable. 1. Harden thin 
pieces of tissue (2 to 5 mm.) for six to twenty-four hours ; 
2. Wash in running water twenty-four hours ; 3. Preserve 
in 80 per cent, alcohol. 

Tissues hardened in corrosive stain quickly and brilliantly 
in nearly all staining solutions. It is the only fixative after 
which the Heidenhain-Biondi triple stain gives good results. 

Orth's Fluid. — Recently Orth has highly recommended 
as a general fixative a solution consisting of the well-known 
Muller's fluid plus 4 per cent, of formaldehyde : 

Bichromate of potassium, 2 to 2.5 ; 

Sulphate of sodium, I ; 

Water, 100; 

Formaldehyde (40 per cent, solution), 10. 

The formaldehyde should be added only at the time of using, 
for in two days the solution becomes darker, and by the 
fourth day a crystalline deposit begins to take place. As 
fixation -is ordinarily complete in three to four days, this 
deposit does not matter. The tissue should not be over 1 
cm. in thickness. Small pieces \ to \ cm. in thickness can 
be readily hardened in the incubator in three hours. The 
specimens should be washed thoroughly in running water 
six to twenty-four hours before placing in 80 per cent, 
alcohol. 

The method is particularly recommended for mitosis, red 
blood-globules, bone, and colloid material (in cystomata, 
etc.), as it gives a very good consistency to the tissues, 
but the histological detail is not so good as after Zenker's 
fluid. The addition of 5 per cent, of acetic acid would 
unquestionably improve it. 
Flamming' s Solution. — 

Osmic acid, 2 per cent, aqueous solution, 4; 

Chromic acid, 1 per cent, aqueous solution, 15 ; 

Glacial acetic acid, I. 

I. Fix in the solution one to three days. 2. Wash in running 
water six to twenty-four hours. 3. Alcohol, 80 per cent. 



262 PATHOLOGICAL TECHNIQUE. 

It is best to keep the osmic acid in a 2 per cent, solution 
and the chromic acid in a I per cent, solution. The mixture 
can then be quickly made up fresh at the time it is needed. 
The best stains after hardening in Flemming are Babes' saf- 
ranin, aniline-gentian-violet, and carbol-fuchsin. 

Pieces of tissue for hardening in Flemming's solution 
should not be over 2 mm. in thickness, because it has very 
slight penetrating properties. 

Hermann's Solution. — 



Osmic acid, 2 per cent, aqueous solution, 4 ; 

Platinic chlorid, 1 per cent, aqueous solution, 15 ; 
Glacial acetic acid, 1. 

This modification of Flemming's solution is perhaps an even 
better fixative than the model on which it is based, but is 
more expensive. It should be employed in the same manner. 
Pianese's Solution. — 

Chlorid of platinum and sodium, 1 per cent. 

aqueous solution (platinic), 15 c.c. ; 

Chromic acid, \ per cent, aqueous solution, 5 " 
Osmic acid, 2 per cent, aqueous solution, 5 " 

Formic acid, C. P., 1 drop. 

Fix small pieces of tissue, not over 2 mm. thick, in the solu- 
tion for thirty-six hours. Wash in running water for twelve 
hours, then 80 per cent, alcohol. Stain paraffin sections by 
Pianese's special methods (see p. 293). 

This fixative and the special staining methods are particu- 
larly recommended for the study of karyomitosis and of the 
so-called cancer bodies. 

Formaldehyde. — The gas formaldehyde (HCOH) is 
soluble in water to the extent of 40 per cent. Solutions of 
this strength are manufactured by different commercial houses 
under the names of formaline, formol, and formalose. The 
best strength of formaldehyde to use for fixing tissues is a 
4 per cent, solution ; that is, 10 parts of the aqueous 40 per 



HISTOLOGICAL METHODS. 263 

cent, solution, no matter what name is given to it, to 90 
parts of water. The addition of 5 per cent, by volume of 
glacial acetic acid to this solution is said to improve its fixing 
properties. 

This fixing reagent penetrates very quickly. Its harden- 
ing action is not understood. It does not precipitate albu- 
minous bodies, but makes them quite firm. It also hardens 
nerve-sheaths, acting toward them and red globules like the 
chrome salts. Formaldehyde is very useful for preserving 
gross specimens, because it gives them a rather tough elastic 
consistence and preserves the normal color better than other 
hardening fluids and also the transparency of many parts, 
such as the cornea. Tissues, such as muscles or the con- 
tents of a multilocular cystoma, which have been made very 
hard by the fixing reagent used, can be softened even when 
mounted in celloidin, so that they can be cut perfectly by 
placing in a 4 per cent, solution of formaldehyde. 

In histological work it is chiefly useful in the preservation 
of nervous tissue and as a fixing reagent for tissue from 
which frozen sections are to be cut, because it improves the 
cutting qualities of the tissue. As a fixative for specimens 
that are to be imbedded in paraffin or celloidin it is not rec- 
ommended unless combined with other reagents, such as 
bichromate of potassium in Orth's fluid, because it does not 
appear to harden the tissue elements sufficiently to enable 
them to resist the shrinking effects of prolonged exposure 
to alcohol and other fluids in the process of imbedding. In 
frozen sections, however, prepared by the method described 
below, this shrinkage of the tissue elements is not apparent, 
probably because prolonged exposure to dehydrating, clear- 
ing, and imbedding agents is avoided. 

"Wright's Method for Frozen Sections. — This method 
has given such satisfactory results as a histological pro- 
cedure, and has proved, after an exhaustive testing in prac- 
tical work, to be such a saver of time, labor, skill, and ex- 
pense in obtaining satisfactory sections adequate for most 
routine purposes, that it seems destined to replace extensively 
the celloidin and paraffin methods. The essential feature of 



264 PATHOLOGICAL TECHNIQUE. 

the method is the fastening of the section to the slide imme- 
diately after cutting, thus keeping even the most fragile or 
irregularly shaped sections intact and smooth during the 
processes of staining, dehydrating, and clearing which are 
carried out on the slide. The fixation of nuclei and cells is 
superior to that effected by alcohol, and there is much less 
shrinkage than in sections prepared by the usual methods. 
Inasmuch as the success of the method depends to a con- 
siderable extent upon the frozen sections being as thin as 
good celloidin sections, special attention is called to the 
points given on p. 241 in regard to the technique of frozen- 
section cutting. The method is as follows : 

1. Fix pieces of the tissue not more than 1 cm. thick in 

4 per cent, aqueous solution of formaldehyde for fifteen to 
twenty-four hours. Thicker masses of tissue should be 
soaked longer. The tissue may remain indefinitely in the 
formaldehyde solution. If the tissue is in small fragments 
or is too soft and friable to yield coherent sections, it may be 
imbedded in gelatin, as described on p. 279. 

2. Trim the piece of tissue with a knife in such a manner 
that it will present a thickness to be frozen of not more than 

5 mm. The other dimensions of the piece of tissue may be 
as large as the freezing box of the microtome will accom- 
modate. 

3. Rinse the piece of tissue for a few seconds in water, 
and place it on the freezing box of the microtome with a few 
drops of water beneath it ; then freeze and cut frozen sections, 
giving careful attention to the directions for cutting such sec- 
tions set down on p. 241. The sections should not be over 
10 or 15 microns in thickness. 

4. Float the sections off the knife into water, and select a 
good one. Spread this section smoothly on a slide. This 
is easily done by passing the slide into the water and under 
the section, while at the same time the section is manipulated 
by means of a small glass rod drawn out to a small probe- 
pointed extremity. The slide should be free from grease. 

5. Drain off superfluous water. 

6. Press the section upon the slide with a piece of smooth 



HISTOLOGICAL METHODS. 265 

blotting-paper, exerting an even but not great pressure with 
the ball of the thumb. The section will adhere to the slide. 1 

7. Without allowing the section to become too dry, pour 
onto it immediately a small quantity of absolute alcohol 
sufficient to cover the section and adjacent parts of the 
slide. After a few seconds drain off the alcohol. 

8. Flow from a bottle quickly and evenly over the section 
and adjacent surface of the slide a thin solution of celloidin 
in equal parts of absolute alcohol and ether, drain off imme- 
diately, blow the breath briskly once or twice on the surface 
of the section, and immerse the slide immediately in water 
for a few seconds. Thus a thin film of celloidin is formed, 
which fastens the section to the slide. The solution of 
celloidin should be almost watery in consistence, and so thin 
that it will form drops readily without stringing. If it is too 
thin, however, it will not hold the specimen on the slide, and 
if it is too thick, the layer on the" slide will become white 
when the slide is immersed in water. The film of celloidin 
on the slide should be so thin as to be almost invisible. 

9. Stain the section by any of the usual methods applied 
to sections affixed to the slide. The thin layer of celloidin 
offers no obstruction to the staining of the section. The 
staining fluid may be heated on the slide, as in the staining 
of tubercle bacilli with fuchsin, without loosening the section. 
The most satisfactory staining of these sections for general 
purposes is with Delafield's hematoxylin, followed by eosin. 
The various methods for staining bacteria in tissues are 
applicable to these sections. 

10. Dehydrate by flooding the section and adjacent por- 
tions of the slide with absolute alcohol. This will remove 
most of the celloidin. It will not, however, loosen the sec- 
tion unless its action is unusually prolonged. 

11. Clear by flooding the preparation and adjacent parts 

1 If the tissue contains much mucoid material or if it has not been thor- 
oughly fixed, the section may stick to the blotter and not to the slide. This 
difficulty will be overcome by covering the section with absolute alcohol for a 
few seconds just before blotting it, draining off, and then proceeding as indi- 
cated in this step. 



266 PATHOLOGICAL TECHNIQUE. 

of the slide with oil of origanum. If parts of the section 
refuse to clear, apply alcohol again and then more oil of 
origanum. When clear, drain off the oil, blot with a piece 
of dry blotting-paper, and mount in balsam. When mounted, 
none of the celloidin will be visible if the proper technique 
has been employed. 

The staining fluids, alcohol, and oil of origanum are con- 
veniently applied from drop bottles. 

Boiling. — Boiling precipitates the soluble albumin in 
tissues as a granular material which can be readily recog- 
nized. The method is used particularly for the demonstra- 
tion of albumin in renal diseases and in edema of the lungs. 
By means of boiling the quickest permanent mounts of 
tissues can be obtained. The method is not advocated on 
account of the shrinkage caused by the heat, but will some- 
times be found useful. 

Small pieces of tissue not over 1.5 cm. in diameter should 
be dropped into the boiling water for one-half to two min- 
utes ; cool quickly in cold water, and make frozen sections, 
or put into 80 per cent, alcohol. Any stain can be used; 
methylene-blue will be found excellent. 

Miiller's Fluid.— 

Bichromate of potassium, 2 to 2.5 grams; 

Sulphate of sodium, 1 gram ; 

Water, 100 c.c. 

Harden tissues six to eight weeks. Change the fluid daily 
during the first week ; once a week thereafter. Ordinary 
tissues are then washed in running water overnight before 
being placed in alcohol. Nervous tissue is transferred di- 
rectly from the fluid to the alcohol. 

This famous hardening solution seems destined before 
long to give way entirely to better fixatives. It hardens 
tissues slowly, evenly, and with little or no shrinkage, but it 
is a poor nuclear fixative, and does not encourage any great 
variety of stains. The sulphate of sodium seems to serve 
absolutely no function. For ordinary tissues it will un- 
doubtedly be replaced by Zenker's or Orth's fluid, both of 



. HISTOLOGICAL METHODS. 267 

which fix very quickly, besides having all its good qualities. 
For nervous tissues formaldehyde followed by other solu- 
tions of the chrome salts is a great deal quicker and better. 
Tellyesniczky has recently recommended the following 
mixture, which has met with considerable favor, and which 
may be regarded as an improved Miiller's fluid : 

Bichromate of potassium, 3 parts.; 

Water, 100 

Glacial acetic acid, 5 " 

Fix thin sections for one to two days ; thicker sections 
longer. Wash out thoroughly in running water. Dehy- 
drate in graded alcohols. 
Marches Fluid. — 

Miiller's fluid, 2 parts ; 

Osmic acid, 1 per cent, aqueous solution, 1 part. 

Place small pieces of tissue in the mixture for five to eight 
days, wash thoroughly in running water, and harden in 
alcohol. For its application to degenerated nerve-fibers 
see page 354. 



DECALCIFICATION. 

Tissues which are to be decalcified should be sawn with 
a fine hair-saw into thin slices, so that they will decalcify 
quickly. It is usually desirable to saw the tissue into pieces 
of proper size for imbedding in celloidin. Very dense bone 
ought not to be over 2 or 3 mm. thick ; softer tissues do not 
need to be thinner than 4 to 6 mm. In cutting sections after 
decalcifying and imbedding it is necessary to throw away the 
first half-dozen sections or so, because the tissue is so lacer- 
ated to a slight depth by the movement of small fragments 
of bone in the process of sawing as to be useless for micro- 
scopic purposes. The extent of the decalcification can be 
tested at any time by thrusting a needle into the tissue. 

The following steps in the decalcification of tissues must 
be carefully borne in mind. 

I. The tissues must first be thoroughly hardened. The 



268 PATHOLOGICAL TECHNIQUE. 

three most useful reagents for this purpose are alcohol and 
Zenker's and Orth's fluids. After the two latter reagents the 
tissues must have been washed thoroughly in water and 
placed in alcohol for at least twenty-four hours. They will 
then be ready for decalcification. 

2. The decalcifying fluid must be used in large amounts, 
and, if necessary, be frequently changed. 

3. After decalcification the tissues must be thoroughly 
washed in running water for twenty-four hours to get rid of 
every trace of the acid. 

4. The tissues finally must be hardened again in alcohol. 
Of the various agents used for decalcifying bone, nitric, 

hydrochloric, chromic, picric, trichloracetic acids, etc., the 
most important is nitric acid. It acts quickly, without swell- 
ing the tissues or attacking injuriously the tissue-elements, 
and does not interfere to any marked degree with any sub- 
sequent staining process. Red blood-globules will be found 
uninjured in tissues hardened in Zenker's fluid even after re- 
maining four days in 5 per cent, nitric acid. This acid is 
used in dilute solution alone or in combination with phloro- 
glucin. 

Directions for Using Nitric Acid. — 1. Decalcify in 
large quantities of a 5 per cent, aqueous solution of nitric 
acid, changing the solution every day for one to four days. 
2. Wash twenty-four hours in running water to remove 
every trace of acid. 3. Harden in 80 per cent., and then 
95 per cent., alcohol. Imbed in celloidin. According to 
Schaffer, it is best to transfer the tissue directly from the 
nitric acid to a 5 per cent, solution of alum for twenty -four 
hours before placing in running water, so as to avoid any 
possibility of the tissue swelling. 

Phloroglucin and Nitric Acid. — Phloroglucin is not 
a decalcifying agent, but is added to nitric acid to protect the 
tissues while allowing a stronger solution of the acid to be 
used than would otherwise be possible. The solution is 
prepared by dissolving 1 gram of phloroglucin in 10 c.c. of 
nitric acid. Solution takes place quickly, with generation of 
considerable heat. The fluid is reddish brown at first, but 



HISTOLOGICAL METHODS. 269 

becomes light yellow in the course of twenty-four hours. 
Dilute with ico ex. of a 10 per cent, solution of nitric acid. 
This gives nearly a 20 per cent, solution of nitric acid. The 
process of decalcification in this fluid is extremely rapid ; a 
few hours only, as a rule, are required. It is not advisable 
to dilute the solution by the simple addition of water, but 
by the use of less acid, because the phloroglucin must be 
present to the amount of 1 per cent, or it will not protect 
the tissues so well. 

The following slower-acting solution may be found useful : 

Phloroglucin, 1 ; 

Nitric acid, 5 ; 

Alcohol, 70 ; 

Water, 30. 

A rather deep single stain with alum-hematoxylin (either 
aqueous solution or Delafield's) will usually be found to give 
the best results with tissues decalcified with nitric acid. It 
is very important to leave the sections after staining in a 
large dish of water overnight, otherwise the stain will not 
be so sharp and clear. 

Sulphurous Acid. — A saturated solution — about 5 per 
cen t. — is used. It works very quickly and causes little 
swelling. The tissues should be carefully washed out in 
running water as after nitric acid. The stock solution 
rapidly grows weak through evaporation if the bottle in 
which it comes is not kept tightly corked. 

Trichloracetic Acid. — A 5 per cent, solution of this 
acid has lately been recommended for the decalcification of 
bone and teeth. It acts more slowly than nitric acid, and 
seems to possess no advantages over it. Tissues must be 
washed out in running water, as after nitric acid. 



IMBEDDING PROCESSES. 

Sections of hardened tissues can be cut with a razor by 
hand, or with a microtome knife after fastening the specimen 
in the microtome clamp either directly or between pieces of 




270 PATHOLOGICAL TECHNIQl 



amyloid liver. Fair sections of firm tissues can often be ob- 
tained in this way. Thinner sections can be got by means 
of the freezing microtome, but these methods are all open 
to the objection that unless the tissue is very cohesive, por- 
tions of it are likely to fall out of the sections. 

The best results would, therefore, naturally be expected 
from some imbedding process, employing a substance to in- 
filtrate the tissues thoroughly and to hold the different parts 
in proper relative position even in the thinnest sections. 

The two substances in common use for this purpose are 
celloidin and paraffin. Each has its advantages and disad- 
vantages. Neither can be employed in pathological his- 
tology to the exclusion of the other. Paraffin affords the 
thinner sections, but they must be small if the best results 
are desired, and cannot be properly handled except when 
fastened to the slide. Hard tissues, like muscle, and tissues 
of varying consistency, like skin, are cut with considerable 
difficulty by the paraffin method. Staining is rather simpler 
than after imbedding in celloidin. 

On the other hand, tissues of almost any consistency or 
size can be cut by the celloidin method, which is also capa- 
ble of furnishing very thin sections. 

Both methods of imbedding should be learned and used. 
Celloidin sections are especially good for general work, for 
studying the extent and relations of pathological processes, 
and for much of the finer histological work. Paraffin sec- 
tions are better for the finest details of processes — for special 
work on special tissues. 

Celloidin. — Schering's celloidin is the best preparation 
of gun-cotton (pyroxylin) to use. It is sold now in a con- 
venient granular form in small bottles. It keeps well, dis- 
solves somewhat slowly, and gives a fairly transparent im- 
bedding mass, which is firm and tough, so that very thin 
sections can be cut. Other forms of gun-cotton are not so 
reliable ; they often contain impurities and do not yield so 
firm an imbedding mass. 

Imbedding in Celloidin. — The process consists in 
soaking the tissues for twenty-four hours to a number of 



HISTOLOGICAL METHODS. 2J\ 

days in two different solutions of celloidin. The two solu- 
tions are spoken of as thin and thick celloidin. To make 
thick celloidin 30 grams of the dry celloidin are dissolved 
in 200 to 250 ex. of a mixture of equal parts of ether and 
absolute alcohol. Diluted with an equal amount of the 
ether-and-alcohol mixture, it forms thin celloidin. 

The steps of the imbedding process are as follows : Pieces 
of tissue which have been properly fixed and finally pre- 
served in 80 per cent, alcohol are first to be cut up with in- 
telligence. They should rarely be over 4 to 8 mm. thick ; 
for most purposes 2 mm. will be found sufficient. Pieces of 
this thickness will furnish several hundred sections, will im- 
bed more quickly than larger masses, and will be more rigid 
when mounted on a block. They should never be broader 
or longer than is necessary to show the whole of the process 
under study. Very thin celloidin sections cannot usually be 
obtained with tissues over \\ to 2 cm. square, and smaller 
dimensions are preferable. Beginners usually imbed larger 
pieces than are necessary. 

The trimmed pieces of tissue are first hardened and de- 
hydrated for twenty-four hours in 95 per cent, alcohol, fol- 
lowed by twenty-four hours in absolute alcohol ; then soaked 
in equal parts of absolute alcohol and ether for the same 
length of time to prepare them for the thin celloidin. In the 
latter they remain at least twenty-four hours, preferably for 
a number of days, if at all thick, for in this solution occurs 
most of the infiltration with celloidin. Finally, the pieces are 
soaked twenty-four hours or more in the thick celloidin. 
They are then mounted on blocks of vulcanized fiber, ex- 
posed to the air for two or three minutes till the surface 
hardens a little, and placed in 80 per cent, alcohol for six to 
twenty-four hours to allow the celloidin to harden. 

Briefly summed up, the steps of imbedding in celloidin are 
as follows : 

1. 95 per cent., followed by absolute alcohol, twenty-four 
hours each. 

2. Ether and absolute alcohol, da, twenty-four hours. 

3. Thin celloidin, twenty-four hours to one or more weeks. 



272 PATHOLOGICAL TECHNIQUE. 

4. Thick celloidin, twenty-four hours to one or mo^e 
weeks. 

5. Mount on blocks of vulcanized fiber: dry a minute or 
two in the air. 

6. Harden celloidin in 80 per cent, alcohol, six to twenty- 
four hours. 

The second step may be omitted if time is pressing. 

Instead of mounting directly from the thick celloidin, it is 
often advisable to allow the celloidin to evaporate until a firm 
mass is obtained. This is particularly true when very loose 
tissues are to be imbedded. 

The simplest method is to place the pieces of tissue, which 
have been soaking in thick celloidin, in proper position in a 
glass dish and pour thick celloidin over them. The dish is 
then covered, but not too tightly, and the ether is allowed to 
evaporate for one or more days until the proper consistency 
of celloidin is reached, so that it can be cut out in blocks 
enclosing the specimens. If the ether evaporates too 
rapidly, place a large dish or a bell-jar over the covered 
dish. Mount the blocks, after they have been cut out and 
trimmed, by dipping the bases in thick celloidin and then 
pressing them on to blocks of vulcanized fiber. In two or 
three minutes they can be placed in 80 per cent, alcohol. 
After the celloidin mounts have been in 80 per cent, alcohol 
for six to twenty-four hours, the celloidin is of the proper 
consistency for cutting. It is best to take a sharp knife or 
an old razor and trim the top of the celloidin down to where 
the first good section of the specimen can be cut ; this will 
save considerable wear on the microtome knife. 

Stepanow 1 has recently recommended the following 
method of imbedding in celloidin for three reasons : it is 
quicker, the infiltration is more perfect, and thinner sections 
are possible. 

1. Dehydrate in alcohol, 95 per cent, or absolute. 

2. Oil of cloves, three to six hours or longer. 

3. Place in the following solution for three to six hours 
or longer : 

1 Zeitschrift f. wissensch. Mikroskopie, 1900, xvii., 1 85. 



H1ST0L GICAL ME THODS. 




Celloidin (dry and in fine granules), 


1.5 gm.j 


Oil of cloves, 


5.0 c.c; 


Ether, 


20.0 c.c; 


Absolute alcohol, 


1.0 c.c. ; 



273 



4. Pour the block of tissue and enough of the solution to 
cover it into a filter of very fine paper, and allow the solu- 
tion to thicken, preferably in a warm place. As the solution 
thickens it becomes clear. 

5. Cut out the block of tissue, and mount in the usual 
way. 

6. Place in 80 per cent, alcohol (or in chloroform for one 
to two hours, followed by 80 per cent, alcohol). 

In cutting, the microtome knife should be fastened very 
obliquely, so that as much of the edge of the knife as pos- 
sible shall be used in making each section. The surface of 
the knife should be kept well wet with 80 per cent, alcohol, 
preferably from an overhanging drop-bottle. 

If the sections curl, as often happens when they are thin, 
they are best flattened by unrolling them on to the surface 
of the knife with a camel's-hair brush just before the last 
edge of celloidin is cut through, as this serves to keep them 
fixed in place during the process. This method can be used 
when the simple transferring of sections from alcohol to 
water is not sufficient to uncurl them. 

Celloidin sections can be stained by nearly all methods, 
without the necessity of removing the celloidin. When 
necessary, however, the celloidin is readily removed by 
placing the sections from absolute alcohol in oil of cloves 
or in the alcohol-and-ether mixture for five or ten minutes, 
and then passing them back through absolute into ordinary 
alcohol. 

To Attach Celloidin Sections to the Slide. — A celloidin sec- 
tion can be fairly well attached to a slide by transferring it 
from water to a slide freshly washed in alcohol and dried 
with a cloth. The section is then to be firmly blotted with 
filter-paper so as to apply it closely to the slide and to re- 
move all wrinkles. It should not be allowed to dry. A 

18 



274 PATHOLOGICAL TECHNIQUE. 

section treated in this way will ordinarily stand considerable 
manipulation without becoming loose. 

Celloidin sections can be more securely attached by trans- 
ferring them from 95 per cent, alcohol to clean slides and 
pouring over them ether-vapor from a bottle half full of 
ether. With a little practice sections can be fastened in a 
few seconds. Follow slowly along the edge of the celloidin, 
and the frills in it will soften down. Then wash the specimen 
with 80 per cent, alcohol to harden the celloidin. 

Imbedding in Paraffin. — Paraffin imbedding is particu- 
larly useful when very thin sections are desired. To obtain 
the best results the pieces of tissue should be small soft, 
and of uniform consistency. In pathological work it is much 
better to cut the sections and to stain them after they are 
fastened to the slide than to stain in the mass beforehand, 
because then a variety of stains may be used. A complete 
or perfect series is not so important as in embryology, but 
with a little care can be obtained. 

The first step in the preparation of hardened tissues for 
the paraffin bath is to cut them into small, thin, square or 
rectangular pieces, not over 1 cm. square, perhaps, for the 
best results, and not over 2 to 3 mm. thick. It should be 
stated, however, that with proper skill, a heavy, sharp knife, 
and a rigid microtome very thin paraffin sections can be ob- 
tained with tissues measuring 4X3 cm. The pieces of 
tissue are then thoroughly dehydrated by soaking first in 95 
per cent, and then in absolute alcohol. From alcohol they 
are put in some substance, such as chloroform or oil of 
cedar, which has the property of mixing with alcohol and 
of dissolving paraffin. From the chloroform they are trans- 
ferred to a saturated solution of paraffin in chloroform, and 
then passed through two separate baths of the melted par- 
affin to get rid of every trace of the chloroform. If oil of 
cedar is used, the specimens are transferred directly from it 
into the melted paraffin, or they may be placed first for 
half an hour or so in chloroform to get rid of the oil of 
cedar. This procedure enables one to make use, for certain 
dense tissues, such as the skin, of the better penetrating 



HISTOLOGICAL METHODS. 2?$ 

powers of the oil, and yet avoid carrying it into the paraffin 
bath. 

One advantage of the chloroform method is that the dura- 
tion in the Hot paraffin, the objectionable feature of the par- 
affin method, is shortened, because the tissues are already 
somewhat infiltrated with paraffin. Another advantage is 
that the paraffin bath purifies itself, because the chloroform 
rapidly evaporates. When oil of cedar is used, the paraffin 
must be renewed frequently. 

The methods of imbedding in paraffin are briefly stated as 
follows : 

Method No. i. 

1. 95 per cent, alcohol, 

2. Absolute alcohol, 

3. Chloroform, 

4. Chloroform saturated with paraffin, 

5. Paraffin bath, two changes, 

6. Imbed and cool quickly in cold water. 



6-24 hours. 


6-24 " 


6-24 " 


6-24 " 


2- 4 " 


6-24 hours. 


6-24 " 


6-24 " 


2- 8 " 



Method No. 2. 

1. 95 per cent, alcohol, 

2. Absolute alcohol, 

3. Oil of cedar, two changes, 

4. Paraffin, three changes, 

until no odor of oil of cedar. 

5. Imbed and cool quickly in cold water. 

In the second method other substances than oil of cedar 
can be used, such as xylol, equal parts of oil of cloves and 
turpentine, or oil of cloves and xylol. 

For imbedding paraffin specimens metallic boxes can be 
used, or forms made round or square from strips of sheet 
lead or tin. Many prefer paper boxes, which can be made 
easily of any size desired from stiff writing-paper. 

Melted paraffin is poured into the paper box to the depth 
of about 1 cm. The pieces of tissue are then placed in the 
box with that side down from which sections are preferred. 
When all the pieces are arranged in order with about half 
a centimeter or more between them, the box is placed on the 



276 PATHOLOGICAL TECHNIQUE. 

surface of a large dish of cold water, on which it floats, so 
that the paraffin may cool quickly without crystallizing. 
Sometimes it is advisable to set the paper box with the 
specimens in it in the paraffin oven for a short while, so as 
to get rid of any bubbles carried in by the specimens. After 
the paraffin has hardened, the paper is removed and the par- 
affin is divided up according to the pieces in it. One of the 
blocks is then fastened to the object-holder by heating the 
latter in a flame until it will just melt the paraffin when the 
block is held in proper position against it. The holder is 
then quickly cooled in cold water. 

The upper surface of the paraffin should now be shaved 
down to the specimen. The four sides are to be carefully 
trimmed ; the upper and lower surfaces should be parallel 
and not cut too close to the specimen, otherwise the sections 
will not adhere to each other; the lateral surfaces should, 
as a rule, be cut close to the tissue, especially if very thin 
sections are desired, because if a rim of paraffin is left it is 
likely to cause wrinkling of the sections. The holder is 
finally carefully adjusted in the paraffin microtome. 

To get good sections which will adhere to each other and 
form a ribbon the temperature of the room must be regulated 
to suit the degree of hardness of the paraffin used. An open 
window will often make all the difference needed to obtain 
good results. The harder the paraffin the warmer the room 
must be. The temperature can be raised by burning a Bun- 
sen flame near the microtome or lowered by the presence of 
a lump of ice. It will often be found advantageous to dip 
the holder and paraffin block into ice water just before cut- 
ting sections. 

The ribbons of sections as cut, usually a slideful, are 
laid on the surface of a large dish of warm water at about 
44 C, and if necessary gently stretched so as to remove 
all wrinkles. Paint the surface of a slide with a thin layer 
of Mayer's glycerin-albumin mixture, wipe off all excess with 
a towel so that only a faint layer is left, dip the slide under 
the sections, arrange them in order, lift the slide, and drain 
off the water. The slide is then placed in a slanting position 



HISTOLOGICAL METHODS. 2JJ 

until dry, when it is put in the incubator for two to twelve 
hours at a temperature of 54 to 6o° C. This process 
attaches the sections firmly to the slide. 

To get rid of the paraffin in the sections they are treated 
with two or three changes of xylol, and then with absolute 
followed by 95 per cent, alcohol. 

If for any reason the celloidin-and-oil-of-cloves mixture is 
used for attaching the sections to the slide, the paraffin is 
removed by means of xylol, followed by origanum or berga- 
mot oil, and finally by 95 per cent, alcohol, because absolute 
alcohol will dissolve the celloidin. 

Serial Sections by the Celloidin Method. — 1. For 
Tissues in General. — With a little care perfect serial sections 
can be made by the following method, and each slide of sec- 
tions can be stained in whatever way seems best. The 
specimen is imbedded, mounted on vulcanized fiber, and 
hardened in 80 per cent, alcohol in the usual way. In cut- 
ting moisten the microtome knife with 95 per cent, alcohol. 
As the sections are cut they are drawn up on the surface of 
the knife and arranged in regular order by means of a camel's- 
hair brush until a slideful is ready. They are then drawn on 
a clean and numbered slide held against the back of the 
knife. After being carefully arranged the sections are fast- 
ened to the slide by means of ether-vapor (see p. 274) poured 
over them from a half-full bottle. Care must be taken that 
every edge of the celloidin is fully softened down. The slides 
are then placed in a jar of 80 per cent, alcohol to be stained 
at leisure. 

2. Another method, often convenient where the stain is of 
little importance, is as follows : The tissue is stained, in bulk, 
in alum-cochineal or some other staining fluid that will pene- 
trate, and then imbedded in celloidin in the usual way. After 
being mounted on vulcanized fiber the specimen is hardened 
in chloroform instead of in 80 per cent, alcohol. From the 
chloroform the specimen is transferred to oil of thyme. 
After it is thoroughly penetrated by the latter it is ready to 
be cut. The knife is to be moistened with oil of thyme. 
The sections as cut are arranged on the knife, and then trans- 



278 PATHOLOGICAL TECHNIQUE. 

ferred to slides placed against the back of the knife. The 
slides covered with sections can be placed under a bell-jar as 
fast as they are ready until all are cut, because the oil of 
thyme evaporates slowly. Balsam and cover-slips can be 
added after the cutting is finished. 

3. Darkschewitsch has recently proposed a comparatively 
simple method for preparing a series of celloidin sections. 
A glass cylinder without a neck, of about the diameter of 
the specimen to be cut, is filled with alcohol. Then a series 
of circles of filter-paper are cut of a size just to fit the bottle, 
numbered in order, and wet with alcohol. Each section is 
removed from the microtome knife by pressing one of the 
paper circles upon it and drawing it off. The paper is then 
inverted so that the section is uppermost, and deposited in 
proper order in the bottle, where the series forms a column, 
each section resting upon a numbered paper. The sections 
can be kept indefinitely. When ready to stain the alcohol 
is poured off, the sections washed with water if necessary, 
and then the staining solution poured into the bottle. Other 
reagents are used in the same manner, or sections can be 
treated with the reagents in flat plates, as they do not readily 
slip off the papers. 

4. Weigert's method for a series of celloidin sections was 
designed especially for the nervous system and is rather 
complicated. The process depends on transferring the sec- 
tions as cut to narrow strips of tissue-paper. To do this 
each section as cut is arranged in proper position close to 
the edge of the knife. Then a strip of tissue-paper twice as 
wide as the section is gently placed upon it, and the sections 
withdrawn from the knife. The success of the process 
depends on having but little alcohol on the knife, other- 
wise the specimen will not stick. Each specimen is placed 
on the paper to the right of the last one. The strips of 
paper when full are kept moist by being placed with the 
specimens uppermost on a moist surface composed of a layer 
of blotting-paper wet with alcohol, covered with a sheet of 
tissue-paper, and lying in a shallow dish. 

When all the sections have been cut, each strip of them 



HISTOLOGICAL METHODS. 279 

is taken in turn and coated on both sides with a thin film of 
celloidin in the following way : A strip of sections with the 
specimens below is first pressed gently down upon the sur- 
face of a slide covered with a thin layer of celloidin. This 
fastens the sections and the paper can be removed. Then a 
thin coat of celloidin is poured over the sections and the 
slide is placed on its edge to drain. When the surface of 
the celloidin is dry, the strips can be marked by a fine brush 
dipped in methylene-blue. As soon as the slides are placed 
in the staining solution the celloidin peels off, taking the 
specimens with it. Later, the strips of specimens can be 
divided as desired. On account of their thickness they 
should be cleared, after dehydrating in 95 per cent, alco- 
hol, in a mixture of xylol 3, carbolic-acid crystals 1. 

To obtain serial sections by the paraffin method it 
is only necessary to avoid losing any of the sections from 
the ribbon as ordinarily cut. Perhaps the easiest and safest 
way is to cut long ribbons, a yard or more in length, and 
to place them on sheets of paper in proper order. They 
can then readily be divided by means of needles into short 
series of any desired number of sections, and fastened to 
numbered slides by means of albumin fixative. 

Wright's Imbedding Method for Frozen Sections. 
— This method has been devised for the purpose of holding 
together, in one sheet, frozen sections of small fragments of 
tissue, such as curettings from the uterus, so that they may 
be manipulated and mounted as one section by the method 
for frozen sections described on page 263. It depends on 
the fact that gelatin exposed to formaldehyde becomes in- 
soluble in water. The method consists in soaking the frag- 
ments of tissue for a few minutes or longer in a warm 20 
per cent, solution of gelatin in water, then placing the 
fragments close together in a watch-glass with enough of 
the melted gelatin to form a layer about 5 mm. thick, and 
allowing the gelatin to solidify, after which the block of 
gelatin inclosing the fragments is cut out of the watch-glass 
and placed in a 4 per cent, aqueous solution of formalde- 
hyde for from eighteen to twenty-four hours. Sections are 



28o PATHOLOGICAL TECHNIQUE. 

then cut from the mass on the freezing microtome, floated 
out in water, and manipulated and stained as described on 
page 241. The sections appear as sheets of gelatin inclos- 
ing sections of the fragments of tissue. The gelatin may 
be constantly kept on hand ready for use in corked test- 
tubes, each containing 8 or 10 c.c. To prevent the growth 
of molds in the gelatin, a little thymol or carbolic acid may 
be added to it. Fragments of tissue already fixed in for- 
maldehyde may also be imbedded in the gelatin as above 
described. The solidification of the gelatin in the watch- 
glass may be hastened by placing the watch-glass in ice- 
water. The action of the formaldehyde on the gelatin may 
be hastened by placing the vessel containing the solution of 
formaldehyde and the gelatin block in the paraffin oven at 
about 55° C. for some hours. If it is desired to do this, it is 
necessary that the gelatin block first be kept at room-tem- 
perature in the formaldehyde solution for at least an hour, 
in order to prevent the melting of the gelatin. 



STAINING SOLUTIONS. 

Hematoxylin and Hematein Stains. — The active 
coloring agent in most hematoxylin stains is hematein, 
which is gradually formed in the ordinary solutions from 
the hematoxylin by oxidation, a process occupying a number 
of days or weeks and spoken of as " ripening." The selec- 
tive staining power of alum-hematoxylin solutions is due to 
the combination of this hematein with alumina. The result- 
ing blue-colored solution is precipitated in the tissues (chiefly 
in the nuclei) by certain organic and inorganic salts there 
present, as, for instance, phosphates. 

Mayer and Unna have shown that it is possible to oxidize 
and to ripen in an instant a solution of alum and hema- 
toxylin by adding to it a little peroxid of hydrogen neutral- 
ized by a crystal of soda. 

By employing hematein or its ammonium salt, instead of 
hematoxylin, Mayer has been able to obtain immediately 
ripened solutions which compare fairly favorably with old 



HISTOLOGICAL METHODS. 28 1 

and well-known solutions prepared from hematoxylin by the 
slow process of ripening. They do not stain any better, 
however, and it is doubtful if, for the present at least, they 
become generally accepted. 

Most solutions of alum and hematoxylin are not stable. 
A continuous chemical change is the formation from hema- 
toxylin, by oxidation, of hematein, which, uniting with the 
alum, gives a bluish or purplish solution. The degree of 
blueness depends largely on the freshness of the alum. As 
the solution becomes older free sulphuric acid is gradually 
formed from the alum, causing the solution to lose its bluish 
or purplish tint and to become reddish. A third chemical 
change is the continuous formation of a precipitate due to 
the further oxidation of the hematein, in consequence of 
which it is always necessary to filter alum-hematoxylin solu- 
tions just before they are used. 

More alum than is needed to combine chemically with the 
hematoxylin is always added to the solution, for the reason 
that it acts as a differential decolorizer, limiting the stain largely 
to the nuclei of the cells. As alum-hematoxylin solutions be- 
come older they stain more quickly, but also more diffusely. 
This diffuseness of staining can be counteracted by adding 
enough alum-water to make the stain precise again. A good 
alum-hematoxylin solution ought not to stain the celloidin 
in which the section is imbedded. If the celloidin stains 
more or less deeply, it shows that the solution requires more 
alum. 

Aqueous Alum-hematoxylin Solution. — 

Hematoxylin crystals, I ; 

Saturated aqueous solution of ammonia alum, 100; 
Water, 300 ; 

Thymol, a crystal. 

The hematoxylin crystals are dissolved in a little water by 
the aid of heat. The combined solution is exposed to the 
light in a bottle lightly stoppered with a plug of cotton. 
The solution will be ripened sufficiently for use in about 



282 PATHOLOGICAL TECHNIQUE. 

ten days, after which time it should be kept in a tightly 
stoppered bottle. The solution is very easily prepared, 
gives beautiful results, and will keep at its best for two to 
three months. The proportions of alum and of hematox- 
ylin are the same as in Delafield's solution. For Zenker 
preparations, which stain very slowly, it will be found more 
convenient to omit the 300 c.c. of water in the above 
formula. 

Delafield's Hematoxylin. — 

Hematoxylin crystals, 4 grams ; 

Alcohol, 95 per cent, 25 c.c; 

Saturated aqueous solution of ammonia 

alum, 400 " 

Add the hematoxylin dissolved in the alcohol to the alum 
solution, and expose the mixture in an unstoppered bottle 
to the light and air for three to four days. 
Filter, and add — 

Glycerin, 100 c.c. ; 

Alcohol, 95 per cent., 100 " 

Allow the solution to stand in the light until the color is 
sufficiently dark, then filter and keep in a tightly-stoppered 
bottle. The solution keeps well and is extremely powerful. 
So long as it is good the solution has a purplish tinge. 

It would seem advisable, both in this solution and in Ehr- 
lich's, to combine the alum, hematoxylin, and the water, and 
to ripen the solution for two or three weeks before adding 
the other ingredients which have a tendency to prevent oxi- 
dation. A fully-ripened solution would then be obtained 
more quickly and surely. 

Bhrlich's Acid Hematoxylin. — 

Hematoxylin crystals, 2 grams ; 

Absolute alcohol, 60 c.c. ; 

Glycerin, 60 c.c. 



Water, 60 

Glacial acetic acid, 3 " J 



I saturated with 



ammonia alum. 



HISTOLOGICAL METHODS. 283 

The solution is to be exposed to the light for a long time 
until it acquires a deep-red color. If it then be kept carefully 
stoppered, its staining powers will remain constant for years. 
The acetic acid is added to prevent the formation of insoluble 
compounds of hematein and as a decolorizer to limit the 
stain to nuclei. 

Mayer's Hemalum. — 

Hematein, or its ammonia salt, I gram ; 

90 per cent, alcohol, 50 c.c. ; 

Alum, 50 grams ; 

Water, 1000 c.c. ; 

Thymol, a crystal. 

Dissolve the hematein or its ammonia salt in the alcohol by 
the aid of heat, and add it to the alum dissolved in the water. 
The solution can be diluted with 20 parts of water or of 
weak alum solution. 

Mayer's acid hemalum is prepared by adding 2 per cent. 
of glacial acetic acid to the above solution. The acid stain 
is more precise than the alkaline. 

Mayer's Glycerin-alum-hematein Solution. — According 
to Mayer's latest investigations, glycerin is the only reliable 
preservative of hematein solutions. Unfortunately, it slows 
the staining power to a considerable extent and makes the 
stain less precise. He recommends the following solution 
for its keeping properties : 

Hematein, 0.4 grams 

(dissolve by rubbing up in a few drops of glycerin) ; 
Alum, 5 grams ; 

Glycerin, 30 c.c. ; 

Water, 70 " 



Mayer's Muchematein. — 




Hematein, 


0.2 grams ; 


Chlorid of aluminum, 


O.I 


Glycerin, 


40 c.c. ; 


Water, 


60 " 



284 PATHOLOGICAL TECHNIQUE. 

Rub up the hematein with a few drops of glycerin, add the 
chlorid of aluminum, and dissolve the mixture in the 
glycerin and water. 

Weig-ert's Alcohol Hematoxylin. — 

Hematoxylin crystals, 10 grams ; 

Alcohol (absolute or 95 per cent), 90 c.c. 

The solution ripens in a week or two to a brown color, and 
keeps perfectly for a long time. It is used only in the 
Weigert stain for myelin sheaths, for which purpose it is 
diluted at the time of using with water and combined with 
carbonate of lithium (see page 344). 

Phosphomolybdic Acid Hematoxylin {Mallory). — 
Hematoxylin crystals, 1.75 grams; 

\ per cent, aqueous solution of phos- 
phomolybdic acid, 200 c.c. 

The hematoxylin will dissolve almost immediately if powdered, 
or it may be dissolved in water by the aid of heat. The 
solution must be exposed to the light in a bottle plugged 
with cotton for five to six weeks before it is fully ripened. 
It will keep for several months, and can be used over and 
over. It is employed for staining the nervous system and 
connective tissue. 

Phosphotung-stic Acid Hematoxylin {Mallory)} — When 
this formula was first published the phosphotungstic acid 
manufactured by Merck was not pure. It contained a trace 
of phosphomolybdic acid, and also some oxidizing agent 
which ripen hematoxylin at once. The acid obtained since 
then sometimes oxidizes hematoxylin and sometimes does 
not. It is a simple matter, however, to ripen the solution at 
once. 

Hematoxylin, O.i gram; 
Water, 80. c.c. 
10 per cent, aqueous solution of phos- 
photungstic acid (Merck), 20. " 

1 Mallory : The Journal of Experimental Medicine, 1 900, v., 19. 



HISTOLOGICAL METHODS. 285 

Dissolve the hematoxylin in a little water by the aid of heat, 
and add it after it is cool to the rest of the solution. If the 
solution does not stain, it may be ripened by the addition of 
any one of 'the following oxidizing reagents: peroxid of 
hydrogen (U. S. P.), 0.2 c.c. ; \ per cent, aqueous solution 
of permanganate of potassium, 10 c.c. ; or 10 per cent, nitric 
acid, 1.5 c.c. 

The best results are obtained by using hematein ammo- 
nium (hematein purissimum does not seem to work quite so 
well) instead of hematoxylin, and allowing the solution to 
ripen spontaneously for several months. Solutions a year 
or more old stain with great intensity. 

If hematein ammonium is used instead of hematoxylin 
and it is desired to ripen the solution at once, use half the 
quantity of any one of the oxidizing reagents mentioned 
above. 

This staining solution will be found particularly useful for 
the demonstration of fibrin and of neuroglia and fibroglia 
fibrils. 

Carmine Stains. — The active staining principle in car- 
mine solutions is carminic acid. In cochineal carminic acid 
is combined with an alkaline base. Carmine itself is a com- 
mercial compound containing carminic acid combined with 
aluminum and calcium. Carminic acid itself does not stain, 
but it forms compounds with certain metals, mainly with the 
aluminum contained in alum, which have selective staining 
properties. 

All of the alkaline and acid solutions made with carmine 
owe their staining properties to carminic acid combined with 
the aluminum, and perhaps also to the calcium contained in 
the carmine. 

Alum Carmine. — 

Carmine, 2 grams ; 

Alum, 5 

Water, 100 c.c. 

Boil twenty minutes, adding enough water to make up for 
that lost by evaporation. When cool, filter and add a 
crystal of thymol to prevent the growth of mould. 



286 PATHOLOGICAL TECHNIQUE. 

Alum Cochineal. — 

Powdered cochineal, 6 grams ; 

Ammonia alum, 6 " 

Water, ioo c.c. 

Boil for half an hour ; add water to make up for that lost 
by evaporation. Filter and add a crystal of thymol. 
Mayer's Alcoholic Carmine (Paracarmine). — 

Carminic acid, i.ogram; 

Chlorid of aluminium, 0.5 " 

Chlorid of calcium, 4.0 grams ; 

70 per cent, alcohol, 100.0 c.c. 

Dissolve cold or warm ; allow to settle, then filter. After 
staining, wash out in 70 per cent, alcohol to which is added 
2.5 per cent, glacial acetic acid if a more purely nuclear 
stain is desired. 

Orth's Lithium Carmine. — 

Carmine, 2.5 to 5 grams; 

Saturated aqueous solution of car- 
bonate of lithium, 100 c.c. ; 
Thymol, a crystal. 

The carmine dissolves at once in the cold solution. When 
used as a counter-stain for bacteria in the Gram-Weigert 
method this solution should be carefully filtered, because 
organisms occasionally grow in it and may give rise to con- 
fusion in the stained preparations. 

Neutral Carmine. — Dissolve, without heating, 1 gram of 
best carmine in 50 c.c. of distilled water plus 5 c.c. of strong 
aqua ammoniae. Expose the fluid in an open dish until it 
no longer smells ammoniacal (about three days) ; then filter 
and put away in a bottle for future use. The odor of the 
solution will soon become bad, but the staining properties 
will remain unaffected. 

Aniline Dyes. — It is extremely important that all aniline 
dyes used in histological work should be obtained, with 
possibly a few exceptions, from Grubler, either directly or 



HISTOLOGICAL METHODS. 287 

from his authorized agents. In no other way is it possi- 
ble to obtain with certainty the results expected. In this 
country Eimer & Amend, of New York City, are the chief 
agents for Griibler. 

Aniline dyes come in the form of a powder or as crystals, 
and most of them keep well in that condition. Methylene- 
blue for one, however, seems to be an exception. After the 
original package has been opened for a short while the dye is 
said to lose in intensity of staining power. It is well to keep 
on hand saturated alcoholic solutions of certain of the dyes, 
because they keep well in that form, and are ready for use 
when a saturated alcoholic solution is wanted. This is par- 
ticularly true of methylene-blue, fuchsin, and gentian-violet. 

Aniline dyes are derived from either aniline or toluidin, or 
from both together. They may be regarded as salts having 
basic or acid properties. The basic colors stain cell-nuclei, 
including bacteria, for which they show a marked affinity. 
The acid colors stain diffusely. The basic dyes most com- 
monly employed in pathological histology are methylene- 
blue, fuchsin, gentian-violet, and safranin. Of the acid 
colors, eosin, picric acid, and acid fuchsin are most in use. 

As a rule, every aniline dye has one or more standard 
solutions which are used largely to the exclusion of others, 
for the reason that, being required for certain purposes, they 
are kept in stock. As they are thus always at hand, they 
are used where simple solutions might be used. For in- 
stance, Lofner's methylene-blue solution is often used, be- 
cause ready and convenient, when a simple aqueous solution 
would do as well. 

In the following pages we have arranged under each dye 
the solutions of it most in use : 

Methylene-blue . 

1. Saturated solution in 95 per cent, or absolute alcohol. 
A stock solution to be used in making other solutions. It 
can be used as a stain by adding 1 part to 9 parts of water. 

2. Aqueous solutions of various strengths are often used, 
and can be made up as needed. 



288 PATHOLOGICAL TECHNIQUE. 

3. Lofflcrs Methylene-blue Solution. — 

Saturated alcoholic solution of methylene-blue, 30 c.c. ; 
Solution of caustic potash in water, 1 : 10,000, 100 " 

This is one of the most useful of the aniline staining solu- 
tions, and will keep for a long time without losing much in 
staining power. 

4. Kith-ne's Methylene-blue Solution. — 

Saturated alcoholic solution of methylene-blue, 10; 
5 per cent, carbolic-acid water, 90. 

This is a stronger staining solution than Loffler's, but the 
resulting stain does not seem so sharp and clear. 

5. Gabbefs Methylene-blue Solution. — 
Methylene-blue, 2 ; 
Sulphuric acid, 25 ; 
Water, 75. 

It is used as a decolorizer and contrast-stain for tubercle 
bacilli. 

6. Unnds Alkaline Methylene-blue Solution. — The strongly 
alkaline solution of methylene-blue recommended by Unna 
for staining plasma-cells has been found extremely valuable 
as a general stain in connection with eosin, which should be 
used first. The solution should be diluted 1 : 10, or 1:5 
for staining : 

Methylene-blue, 1 ; 

Carbonate of potassium, 1 ; 

Water, 100. 
(For method of using see page 321.) 

7. Unnds Polychrome Methylene-blue Solution. — The poly- 
chrome methylene-blue solution, much used by Unna in 
various staining methods, is an old alkaline solution of 
methylene-blue, of which the above is the original formula, 
in which, in consequence of oxidation, methyl-violet and 
methylene-red have formed. Months are required for the 
process of oxidation to take place. The ripened solution 
may be obtained from Grubler. 



HISTOLOGICAL METHODS. 289 

8. Sahli's Borax Methylene-blue Solution. — 

Saturated aqueous solution of methylene-blue, 24 ; 

5 per cent, solution of borax, 16; 

Water, 40. 

Mix, let stand a day, and filter. 

Puchsin. 

1. Saturated alcoholic solution to be kept in stock. 

2. Ziehl-Neelsoij s Carbol-fuclisin. — 

Saturated alcoholic solution of fuchsin, 10 c.c. ; 

5 per cent, carbolic-acid water, 90 " 

This solution is very powerful, stains quickly, keeps well, 
and can be employed for a variety of purposes. 

3. Aniline-fuchsin. — 

Saturated alcoholic solution of fuchsin, 16 c.c. ; 

Aniline-water, 84 

Gentian- violet. 
This dye is not a definite chemical substance, but a mix- 
ture of crystal-violet, methyl-violet, and dextrin. 

1. Saturated alcoholic solution to be kept in stock. 

2. Ehrliclis Aniline-gentian-violet. — 

Saturated alcoholic solution of gentian-violet, 16 c.c; 
Aniline-water, 84 " 

During the first few hours after the solution is made con- 
siderable precipitation takes place> so that it is best not to 
use it for twenty-four hours. After about ten days it begins to 
lose its staining power. (See under methyl-violet, page 290.) 
Zenker recommends a solution without alcohol : Dissolve 
the gentian-violet directly in the aniline-water. The color is 
said to be less easily removed from tissues when this solu- 
tion is used. 

3. Stirling's Solution of Gentian-violet. — 

Gentian-violet, 5 grams ; 

Alcohol, 10 c.c. ; 
Aniline, 2 " 

Water, 8S " 

19 



29O PATHOLOGICAL TECHNIQUE. 

This solution is said to keep remarkably well. 
4. Cavbol-gentian Violet. — 
Saturated alcoholic solution of gentian-violet, 10 c.c. ; 
5 per cent, carbolic-acid water, 90 " 

Safranin. — Two of the many preparations by this name 
have been found especially useful : 

1. Safranin O soluble in water. 

2. Safranin soluble in alcohol. 

The three following solutions of safranin can be thoroughly 
recommended : 

1. Saturated aqueous solution of "safranin O soluble in 
water " (to be made with the aid of heat). 

2. A mixture of equal parts of — 

A saturated aqueous solution of " safranin O soluble 

in water." 
A saturated alcoholic solution of " safranin soluble in 

alcohol." 

3. Babes' Aniline Safranin. — 

2 per cent, aniline-water, 1 00; 

" Safranin O soluble in water," in excess. 

Saturate the solution by heating it in a flask set in hot water 
to 60-80 C. ; filter. 

This solution is extremely powerful, stains almost in- 
stantly, and will keep about two months. 

Methyl- violet. — 1. Aqueous solutions of various strengths, 
\ to 2 per cent, keep well and are used for staining nuclei, 
bacteria, and amyloid. 

2. Methyl-violet can be used instead of gentian-violet in 
Ehrlich's solution. Weigert recommends two permanent 
stock solutions by means of which the aniline oil — methyl- 
violet solution — can be made up easily when wanted. 

Solution 1. — Absolute alcohol, 33; 

Anilin oil, 9; 

Methyl-violet in excess. 

Solution 2. — Saturated aqueous solution of methyl-violet. 



HISTOLOGICAL METHODS. 29 1 

The staining solution consists of — 

Solution 1, 1 ; 

Solution 2, 9. 

This mixture will keep at the most for fourteen days. 

3. For staining neuroglia-fibers Weigert employs a satu- 
rated solution made with the aid of heat in 70-80 per cent, 
alcohol. 

Bismarck Brown. — The most common solutions are the 
following : 

1. A 1 per cent, aqueous solution. 

2. A saturated aqueous solution made by boiling (3-4 per 
cent.). 

3. A saturated solution in 40 per cent, alcohol (2-2J per 
cent.). 

Unlike other aniline colors, Bismarck brown will keep in 
glycerin mounts and can be fixed in nuclei by acid alcohol. 
The stain is not used so much as formerly, except as a con- 
trast stain in Gram's method and for photographic purposes. 
Other basic stains less frequently used, and then generally 
in aqueous solutions, are dahlia, methyl-green, iodin-green, 
and thionin. 

Diffuse Stains. — i . Eosin is sold in two forms — as " eosin 
soluble in water," and as " eosin soluble in alcohol." The 
first is to be preferred, because a greater degree of differen- 
tiation in stain can be obtained with it. Keep on hand a 
saturated aqueous solution and dilute with water as needed. 
The strength of solution to be used varies somewhat with 
the tissue and the reagent in which it has been fixed, but 
generally lies between -^ and \ per cent, when the eosin is 
used after a hematoxylin stain. These dilute solutions 
should contain 25 per cent, of alcohol, otherwise they will 
not keep well. When eosin is employed before an aniline 
dye such as methylene-blue, a 5 per cent, or even a 
saturated solution should be taken. 

2. Picric Acid. — Saturated alcoholic and aqueous solu- 
tions should be kept in stock, to be diluted as needed. 

3. Van Gieson's Picro-fuchsin Solution. — This valuable 



292 PATHOLOGICAL TECHNIQUE. 

solution was originally made by adding to a saturated 
aqueous solution of picric acid enough of a saturated 
aqueous solution of acid fuchsin to give to the fluid a deep 
garnet-red color, and for certain purposes, as in staining 
after Zenker's fluid, this strong solution is to be preferred. 
Freeborn has recently given more precise directions for 
making up the solution according to the purpose for which 
it is to be used. 

For Connective Tissue. — (See page 322). 
1 per cent, aqueous solution of acid fuchsin, 5 c.c. ; 
Saturated aqueous solution of picric acid, 100 " 

For the Nervous System. — (Seepage 329). 

1 per cent aqueous solution of acid fuchsin, 15 c.c. ; 

Saturated aqueous solution of picric acid, 50 " 

Water, 50 " 

Picro-nigrosin (Martinotti). — Dissolve picric acid and 
nigrosin to saturation in 70 per cent, alcohol. 

Combination Stains. — Biondi-Heidenhain Staining 
Solution. — 

Saturated aqueous solution of orange G, 100; 

Saturated aqueous solution of acid fuchsin or 

rubin S, 20; 

Saturated aqueous solution of methyl-green, 50. 
(About 20 gm. rubin S., 8 gm. orange G., and 8 gm. 
methyl-green ; dissolve in 100 c.c. of water.) 

Make up the separate solutions and let them stand for seve- 
ral days with excess of coloring matter (shaking the bottles 
occasionally) until they are saturated. Then mix the solu- 
tions. For staining, dilute the combined solution with water 
1 : 60 to 1 : 100. 

The following tests are used for finding out if the proper 
combination has been obtained: The addition of acetic acid 
should make the solution redder ; a drop of the solution on 
filter-paper should make a blue spot with green in the center 
and orange at the periphery. If a red zone appears outside 
of the orange, then too much acid fuchsin is present. 



HISTOLOGICAL METHODS. 293 

Pianese's Staining Solutions and Staining Meth- 
ods. — The following stains, devised by Pianese, are recom- 
mended by him particularly for the study of cancer, but will 
be found useful in many lines of histological investigation. 
The first two were used by him for tissues hardened in cor- 
rosive sublimate or in Zenker's fluid ; the others, only after 
his special fixative (given on page 262). The methods are 
intended for paraffin sections : 

1. Carmine and Picro-nigrosin.— 1. Stain in neutral or 
lithium carmine. 

2. Decolorize in acid alcohol. 

3. Wash in water. 

4. Absolute alcohol. 

5. Aniline-gentian-violet, ten minutes. 

6. Iodin solution, two to three minutes. 

7. Absolute alcohol, so long as any color is discharged. 

8. Saturated aqueous solution of picric acid and of nigro- 
sin, five minutes. 

9. Decolorize in a 1 per cent, alcoholic solution of oxalic 
acid. 

10. Water, several minutes. 

11. Absolute alcohol. 

12. Oil of bergamot. 

13. Balsam. 

Nuclei, red ; cell-protoplasm, light olive-green ; connec- 
tive tissue, dark olive-green ; elastic fibers, bluish ; bacteria 
and blastomycetes, violet. 

II. Methylene-blue and Eosin in Borax Solution. — 
Keep three solutions on hand : 

(a) Saturated solution of methylene-blue in a saturated 
aqueous solution of borax. 

(b) \ per cent, solution of " bluish eosin " in 70 per cent, 
alcohol. 

(c) Saturated aqueous solution of borax. 

For use mix together 2 parts of the filtered solution a, 1 
of b, and 2 of c. The different steps of the staining pro- 
cess are as follows : 



294 PATHOLOGICAL TECHNIQUE. 

1. Absolute alcohol. 

2. Staining solution, ten to twenty minutes. 

3. Decolorize in a 1 per cent, solution of acetic acid. 

4. Wash in water. 

5. Absolute alcohol. 

6. Xylol. 

7. Xylol balsam. 

Nuclei, blue ; red blood-globules, cell-protoplasm, granules 
of eosinophiles, connective tissue, etc., rose-red. 

III. a. Malachite-green, Acid Fuchsin, and Nigrosin. — 
Malachite-green, 1. gram ; 

Acid fuchsin, .4 " 

Nigrosin, .1 " 

Water, 50 c.c. ; 

Alcohol saturated with acetate of copper, 50 

1. Absolute alcohol. 

2. Stain in 20 drops of above solution diluted with 10 c.c. 
of distilled water for twenty-four hours. 

3. Decolorize in a J per cent, aqueous solution of oxalic 
acid. 

4. Wash in water. 

5. Absolute alcohol. 

6. Xylol balsam. 

Resting nuclei, light red; protoplasm, reddish yellow. In 
the karyokinetic figures, nuclein green ; nbrillae of the achro- 
matic spindle and of the mitoma, bright red; centrosome 
and polar bodies, red ; the rest of the cell-body, a reddish- 
yellow color. 

III. b. Malachite-green, Acid Fuchsin, and Martius 
Yellow. — 

Malachite-green, .5 gram; 

Acid fuchsin, .1 " 

Martius yellow, .01 " 

Distilled water, 150 c.c; 

Alcohol, 96 per cent, 50 

1. Stain in the solution without diluting, half an hour. 

2. Absolute alcohol. 



HISTOLOGICAL METHODS. 295 

3. Xylol. 

4. Xylol balsam. 

Nuclei of resting and dividing cells, green ; cell-protoplasm, 
connective tissue, etc., rose-colored ; " cancer-bodies," mainly 
red, but in masses of them some are red and some green. 

IV. Acid Fuchsin and Picro-nigrosin. — 
Saturated alcoholic solution of acid fuchsin, 6 drops ; 
Martinotti's picro-nigrosin, 8 " 
Distilled water, 10 c.c. 

1. 70 per cent, alcohol. 

2. Stain in the solution six hours. 

3. Decolorize in dilute acetic acid. 

4. Absolute alcohol. 

5. Xylol. 

6. Xylol balsam. 

Resting nuclei, red ; nuclein of karyokinetic figures, yellow : 
cell-protoplasm, dark olive-green ; " cancer-bodies," mainly 
olive-gray, but some or portions of them may be ruby-red. 

V. Light Green (Lichtgriin) and Hematoxylin. — 
Ehrlich's acid hematoxylin, 15 c.c. 
Saturated solution of Lichtgrun in 70 per cent. 

alcohol, 5 " 

Distilled water, 15 " 

1. Distilled water. 

2. Stain in above mixture half an hour. 

3. Wash thoroughly in several waters. 

4. Alcohol. 

5. Oil of bergamot. 

6. Balsam. 

Nuclei, green ; " cancer-bodies " take the hematoxylin stain. 

VI. Acid Fuchsin and Hematoxylin. — 

Ehrlich's acid hematoxylin, 1 5 c.c. 

1 per cent, solution of acid fuchsin in 70 per 

cent, alcohol, 15 " 

Distilled water, 1 5 " 

Stain as in V. 



296 PATHOLOGICAL TECHNIQUE. 

Nuclei, red ; protoplasm, brick-red ; " cancer-bodies " take 
the hematoxylin stain. 

Orcein, a vegetable dye obtained from certain tinctorial 
lichens, is used mainly for staining elastic fibers. It is 
soluble in alcohol, and is employed either in a neutral or 
acid (HC1) alcoholic solution. 

loditt is the oldest of the histological stains, but is now 
but little used for that purpose. 

The tincture of iodin, a saturated solution in alcohol, is 
used for getting rid of the precipitate of mercury formed in 
tissues fixed in corrosive sublimate or in Zenker's fluid. 

I/Ugol'S Solution, a solution of iodin in water containing 
iodid of potash, is of varying strength. Iodin in this form 
is much used as a test for starch, amyloid, glycogen, and 
corpora amylacea. In Gram's stain and its modifications iodin 
produces some chemical change in the coloring material em- 
ployed, in consequence of which, when appropriate deodor- 
izers are used, the stain remains fast in certain structures, 
while from others it is easily entirely extracted. 

The strength originally employed by Gram for his stain- 
ing method was — 

Iodin, I gram ; 

Iodid of potash, 2 grams ; 

Water, 300 c.c. 

Weigert in his modification of this method employed a 
stronger solution : 



-t> 



Iodin, I gram ; 

Iodid of potash, 2 grams ; 

Water, 100 c.c. 

Recently he has recommended the following strength both 
for fibrin and for neuroglia-fibers : 

Iodid of potash, c grams 1 , .,, . ,. 

r ' J & > saturated with iodin. 

Water, 100 c.c. J 

The only difference in the action of the various solutions 



HISTOLOGICAL METHODS. 297 

probably is that the strong solution acts practically instan- 
taneously, while the weaker solutions require some little time. 
Acid Alcohol [Ortlis Discharging Fluid). — 

Hydrochloric acid, 1 c.c. ; 

70 per cent, alcohol, 99 " 

Aniline Water {Aniline-oil Water). — Shake together 5 
parts of aniline with 95 parts of water, and filter the re- 
sulting milky fluid. It should come through perfectly clear. 

Carbolic-acid water is made in like manner by shaking 
together 5 c.c. of melted carbolic-acid crystals and 95 c.c. 
of water. The solution should be filtered. 

Mayers glycerin-albumin mixture for attaching 
paraffin sections to slides is composed of equal parts of the 
white of egg and of glycerin. The mixture should be thor- 
oughly beaten and then filtered, or after standing for some 
time can be decanted. Add a little camphor or carbolic acid 
to prevent decomposition. Egg-albumin is dissolved by 
acids and alkalies, so that when such reagents are to be 
used the sections are best attached to the slide by some 
other substance. For this purpose Schdllibaum s solution, 
of celloidin 1 part in 3 or 4 parts of oil of cloves, is often 
useful. Cover the slide with a thin layer of the solution. 
Arrange the sections in order on the slide and place it in 
the thermostat at 54 to 6o° C. for several hours, or heat 
for a few seconds to half a minute over the flame until the 
oil of cloves runs together in drops. After cooling, remove 
the paraffin with xylol, pass through origanum oil to 95 per 
cent, alcohol, and proceed as with other paraffin sections. 

Clearing Reagents. — The object of clearing reagents 
is to render certain tissue-elements more prominent than 
others. This result may be brought about by dilute acetic 
acid (2-5 : 100), which swells up the ground substance, so 
that nuclei, elastic fibers, fat, myelin, and micro-organisms 
are more distinct, or by alkalies, which destroy the cells and 
ground substance and leave only elastic fibers and bacteria 
but little changed. This method is used almost wholly for 
fresh tissues. 



298 PATHOLOGICAL TECHNIQUE. 

The same result is more commonly obtained by soaking 
the tissues in substances which by reason of their high index 
of refraction render the tissues more or less transparent. 
Any structure which it is desirable to study is usually pre- 
viously stained and thus easily rendered prominent. This 
second method is most applicable to hardened tissues. 

For soaking and clearing the tissues a variety of reagents 
of different chemical properties are used. Glycerin and 
acetate of potash are not so much employed as formerly, 
because balsam mounts are more generally preferred. Of 
the other reagents (ethereal oils and coal-tar products), the 
the choice depends mainly on two factors — the kind of stain 
which has been employed, and the substance in which the 
sections have been imbedded. Many of the clearing re- 
agents either dissolve celloidin or will not clear it from 95 
per cent, alcohol, and nearly all of them will extract aniline 
colors more or less rapidly. 

Most of the clearing reagents can be used after hema- 
toxylin and carmine stains. For celloidin or paraffin sections 
stained by either of them oleum origani cretici, oil of ber- 
gamot, or the mixture of the oils of cloves and thyme is 
recommended in the order given. 

For aniline stains the best clearing reagent is xylol, which, 
however, clears directly only from absolute alcohol. It can 
be used, however, for celloidin or other sections dehydrated 
in 95 per cent, alcohol by a simple method original with 
Welch, and lately brought into notice by Weigert. Blot 
the section on the slide with smooth soft filter-paper, and 
then pour on a few drops of xylol ; repeat the blotting, fol- 
lowed by xylol two or three times, and the section will be 
found to be perfectly clear. 

Oleum Origani Cretici. — Colorless to light brown in 
color ; clears readily from 95 per cent, alcohol without dis- 
solving celloidin ; affects aniline colors slowly. Ordinary 
origanum oil is impure oil of thyme, and should not be 
used. 

Oil of Berg-amot. — Light green in color ; clears quickly 
from 95 per cent, alcohol ; does not dissolve celloidin, but 



HISTOLOGICAL METHODS. 299 

after repeated use of the same lot of oil it will sometimes 
soften it a little. Affects aniline colors slowly, with the ex- 
ception of eosin, which it extracts very quickly. 

Oil of Cloves. — Straw-colored; clears quickly from 95 per 
cent, alcohol ; dissolves celloidin ; extracts aniline colors, 
especially methylene-blue. 

Oil of Thyme. — Colorless ; clears readily from 95 per 
cent, alcohol ; makes sections brittle ; does not dissolve cel- 
loidin ; affects aniline colors. 

Oil of Lavender. — Clears celloidin sections readily from 
95 per cent, alcohol. 

Oil of Cedar- wood. — Pale straw-color ; clears from 95 per 
cent, alcohol, but, unfortunately, clears celloidin sections very 
slowly ; does not affect aniline colors. 

Aniline {Aniline Oil). — Colorless when perfectly pure and 
fresh, but soon oxidizes and turns brown ; does not dissolve 
celloidin ; clears readily from 70 per cent, alcohol ; will clear 
from water by Weigert's method; extracts aniline colors 
slowly. 

Xylol. — Colorless ; does not dissolve celloidin ; does not 
affect aniline colors ; clears directly only from absolute alco- 
hol ; but will clear even celloidin sections from 95 per cent, 
alcohol if they be blotted on the slide, and the xylol be then 
poured over them ; the process of blotting followed by xylol 
must be repeated two or three times. 

Dunham's Mixture of the Oils of Cloves and Thyme. — 
Excellent for sections stained in hematoxylin or carmine. 
Not nearly so expensive as pure origanum or bergamot oil. 

Oil of cloves, I part; 

Oil of thyme, 4 parts. 

Filter if cloudy ; clears celloidin sections readily from 95 per 
cent, alcohol without dissolving the celloidin. 

Weigert's Mixture of Carbolic Acid and Xylol. — 
Carbolic-acid crystals, I part ; 

Xylol, 3 parts. 



3<DO PATHOLOGICAL TECHNIQUE. 

Recommended for clearing thick sections of the central 
nervous system after carmine and hematoxylin stains only. 
The next mixture is more used now-a-days. 
Weigert's Mixture of Aniline and Xylol. — 

Aniline, 2 parts ; 

Xylol, I part. 

Mounting Reagents. — The most generally used reagent 
for permanent mounts is Canada balsam. Damar and colo- 
phonium are only exceptionally preferred. 

Canada balsam occurs in commerce as a very thick, tena- 
cious, pale, straw-colored fluid. It should be evaporated 
over a water-bath to drive off all volatile substances, which 
might affect aniline colors, until it becomes solid and brittle 
on cooling. Dissolve it then in xylol, which does not affect 
aniline colors, to a rather thin, syrupy consistency. Two 
pounds of Canada balsam will evaporate to about one 
pound ; add xylol enough to make the mixture up to two 
pounds. In this condition it is often called xylol balsam. 

Canada balsam has a high index of refraction, so that tis- 
sues mounted in it become very transparent, and only those 
parts are visible which are stained. Other solvents of Canada 
balsam, such as chloroform and benzine, may be used, but 
cannot be recommended for sections stained with aniline 
colors. For tissue stained with osmic acid, cldoroform bal- 
sam, prepared in the same way as xylol balsam, should 
always be used, otherwise the osmic acid stain will fade 
rapidly. 

Damar has a lower index of refraction than Canada bal- 
sam ; is soluble in xylol, chloroform, etc.; dries slowly, and 
is generally recommended for Golgi preparations. 

Colophonium dissolved in benzine is employed by Nissl 
for mounting stained preparations of ganglion-cells. 



HISTOLOGICAL METHODS. 3OI 

METALLIC STAINS OR IMPREGNATIONS. 

Experimental investigation has shown that certain metals 
can be used for staining certain tissue-elements, either be- 
cause they are directly reduced from solutions of appropriate 
salts or because they are taken up and retained by certain 
tissue-elements, which are rendered prominent when the 
metallic salt is reduced later. The most valuable metals for 
this purpose are silver, gold, and osmium. 

Silver is used, generally in the form of silver nitrate, to 
stain of a brown or dark-brown color the cement substance 
between epithelial and endothelial cells and the ground sub- 
stance of connective tissue. The method finds its chief use 
in pathology in demonstrating the endothelial covering of a 
doubtful surface, in outlining the endothelial cells of patho- 
logically altered blood- and lymph-vessels, and in staining 
the ground substance of the connective tissue of the cornea 
when that organ is used experimentally for the study of in- 
flammation. In combination with certain other salts, espe- 
cially bichromate of potassium, nitrate of silver is much em- 
ployed in the Golgi methods to stain ganglion-cells and their 
processes in the central nervous system. 

The difficulty of the silver method lies in the fact that the 
salt forms with albuminous fluids granular and thread-like 
coagula which can easily give rise to false pictures. For 
this reason the method is limited almost entirely to natural 
surfaces, which should be washed off with water or a 2 
per cent, solution of nitrate of sodium before the silver solu- 
tion is applied. It is generally advisable to use the nitrate 
of silver in a very dilute solution, 1 : 250 or 500. The solu- 
tion is allowed to act on the surface for about a minute, and 
is then washed off with water. The tissue is next exposed 
in water to the action either of sunlight or of diffuse light. 
The outlines of the cells soon appear as dark lines, brown to 
black in color. The tissue to be stained should be kept 
stretched, because a precipitation of the silver occurs 
wherever there is a fold in the surface. Although nitrate 



302 PATHOLOGICAL TECHNIQUE. 

of silver penetrates but a slight distance, it is possible to 
stain the outlines of the endothelial cells of the lymphatics 
and blood-vessels as well as the ground substance of the 
connective tissue — in a rabbit's diaphragm, for instance — by 
treating the upper or lower surface with the silver solution. 
The thoracic organs should be removed, and then the upper 
surface of the tendinous portion of the diaphragm left in 
situ is exposed to the action of the silver salt in the manner 
already described. 

The outlines of the endothelial cells of blood-vessels are 
usually stained by injections of the silver salt through an 
artery. In the same way the limits of the epithelial cells 
of the alveoli of the lung can be stained by injections through 
a bronchus. 

Although generally employed in solution, nitrate of silver 
is sometimes used in the solid form, and for the cornea this 
method is preferable. Chloroform the animal, preferably a 
rabbit, deeply ; rub the cornea with a stick of nitrate of 
silver hard enough to remove the surface epithelium. Allow 
the salt to act about ten minutes, then kill the animal, re- 
move the eye, cut out the cornea, wash it, and expose to 
diffuse daylight for half an hour. It is then placed in a 
mixture of glycerin and water, 30 parts to 70, very slightly 
acidulated with acetic acid (about y 1 ^ per cent.) for twenty- 
four hours, so as slightly to swell and to soften the tissues. 
Sections of the cornea are best made with the freezing 
microtome. Incise the periphery a little at four points 
equally distant from each other, so that the cornea will lie 
flat. A direct stain with alum-hematoxylin gives by all odds 
the best results. The sections may be mounted in glycerin 
or balsam. The latter method is perhaps the better. De- 
hydrate the sections in 50 per cent, then in 70 per cent., 
alcohol, clear in aniline oil, wash with xylol, and imbed in 
balsam. This method avoids the shrinkage which is caused 
by using strong alcohol. 

Gold, in the form of the simple or double chlorid, is em- 
ployed to stain the protoplasm of cells of connective tissue, 
and more particularly the axis-cylinders of nerve-fibers and 



HISTOLOGICAL METHODS. 303 

their terminal processes. Like nitrate of silver, it acts as a fix- 
ing and hardening reagent as well as a stain. Unfortunately, 
it penetrates tissues but a very slight distance, and, so far as 
staining is concerned, is inconstant in action. Its chief use 
in pathology is in connection with experimental work on the 
cornea and in regeneration. The conditions under which 
the reduction of the gold salt takes place are not exactly 
understood, but both penetration and reduction are aided 
by the action of organic acids, such as formic, citric, and 
tartaric acids, on the tissues both before and after the treat- 
ment with the gold salt. Of the many methods proposed, 
the following are recommended: 

Lowit's Formic-acid Method. — 1. Place very small bits 
of fresh tissue in a mixture of formic acid 1 part, and water 
1 to 2 parts, until they become transparent (a few seconds 
to several minutes). 

2. Transfer to chlorid of gold, 1 to 1.5 parts to 100 of 
water, for fifteen minutes. 

3. Formic acid, 1 part to water 3 parts, for twenty-four 
hours. 

4. Concentrated formic acid twenty-four hours. Preserve 
in glycerin or balsam. 

All the steps except the first should be performed in the 
dark. 

Ranvier's Formic-acid Method. — 1. Boil together 8 c.c. 
of a 1 per cent, solution of chlorid of gold and 2 c.c. of 
formic acid. When the solution is cold place very small 
bits of tissue in it for one hour, in the dark. 

2. Wash quickly in water. 

3. Expose to diffuse light in a mixture of formic acid 10 
c.c. and water 40 c.c. Reduction takes place slowly (twenty- 
four to forty-eight hours). 

4. Harden in 70 per cent., then 90 per cent., alcohol in 
the dark. 

Osmic Acid (perosmic acid, osmium tetroxid) is used as 
a fixing reagent and for staining fat and myelin, by which it 
is reduced. As osmic acid is quickly reduced by organic 
substances, care must be taken in making up the solution. 



304 PATHOLOGICAL TECHNIQUE. 

Remove the label from the sealed tube in which the acid. 
comes, and place the tube, after cracking off one end, in a 
glass-stoppered bottle containing enough water to make a 
2 per cent, solution. If desired, the tube can be broken 
after it is in the bottle by violent shaking. It should be 
borne in mind that osmic acid is very-irritating to the' bron- 
chial mucous membrane. 

In a I or 2 per cent, solution osmic acid is used to stain fat 
in teased preparations or frozen sections of fresh tissues. In 
Marchi's method it is used to stain fat in tissues which have 
been hardened for some time in Muller's fluid. As a fixing 
reagent it is usually combined with other reagents, as in Flem- 
ming's solution, both for its property as a fixative and for 
the purpose of staining any fat present. 

Preparations stained in osmic acid may be kept indefinitely 
in alcohol. When sections are mounted they should be 
cleared in chloroform, and preserved in chloroform balsam 
prepared in the manner described elsewhere. Xylol and 
other clearing reagents cause the stain to fade. 



STAINING riETHODS. 

The purpose of staining is to render prominent the differ- 
ent tissue-elements, so that they may be readily recognized 
and studied. The constant tendency now-a-days is toward 
selective or differential staining methods, by which but one 
tissue-element will be colored to the exclusion of all others, 
or at least of any element that might be confused with it 
morphologically. These selective stains, which really are 
micro-chemical color reactions, enable us to differentiate 
from each other with ease and accuracy cellular and inter- 
cellular elements, or pathological products which otherwise 
look alike. 

The list given on page 305 does not pretend to be either 
complete or perfect in arrangement, but will give some idea of 
the various elements which we wish to stain. Those for 



HISTOLOGICAL METHODS. 



305 



Cell. 



f Nucleolus. 
Resting nucleus. 
Linin. 



Nucleus. 



Bacte 



li: 



Granules. \ 



Protoplasm. 



Cuticle. 



Do not stain by Gram. 
Stain by Grain. 
3. Slain by tubercle-bacillus method. 
Nucleus of ameba coli. 
r Centrosome and polar bodies, 
f Mastzellen. 
Plasma-cell of Unna. 

(Five kinds of gran- 
ules described by 
Ehrlich. 
NissFs granules in ganglion-cells. 
Dendritic processes of ganglion-cells. 
Axis-cylinder and terminal processes. 
Contractile ele?nents of striated muscle-fiber. 
Red blood-globules. 
*. Cilia of bacteria. 
Certain dots or lines in ependy'mal cells. 
So-called cilia in certain renal cells. 
Bile- cap ilia ries . 



Intercellular 
substances. 



Pathological 
products. 



20 



Cement substance of epithelial and endothelial cells. 

Ground stibstance of connective tissue. 

Connective-tissue fibrillce and reticulum. 

Fibroglia fibrillce. 

Myoglia fibrillce. 

Myxomatous tissue ; mucin. 
\ Elastic fibers. 

Intercellular substances of cartilage. 

Ground substance of bone. 
j Myelin. 

Neurogliafibers. 

Clubs of actinomyces. 
l_ Capsules of bacteria. 



Fibrin. 
Mucin. 
Amyloid. 
Glycogen. 
Hyalin. 
Colloid. 
Keratohyalin. 
y E lead in. 



Hyaline substances. 

Fat. 

Hemosiderin. 

Hematoidin. 

l Hemoglobin. 



306 PATHOLOGICAL TECHNIQUE. 

which we now possess more or less perfect differential stains 
are printed in italics. 

The simplest selective stain is, of course, that for nuclei, 
and it can be obtained with a great variety of staining re- 
agents. The most difficult element to stain differentially, 
although it can be done under certain conditions with a fair 
amount of success, is probably the axis-cylinder and its ter- 
minal processes. 

Tissue-elements and pathological products differ from 
each other, not only in form and consistency, but also in 
chemical properties. While perfect preservation of form is 
sufficient to distinguish certain cells or elements from each 
other — as, for instance, polynuclear leucocytes from lymph- 
oid cells — differentiation based on micro-chemical tests is 
always to be preferred when possible. A few of the tests 
employed are colorless, like the precipitation of mucin by 
acetic acid. Certain tests, like the methylene-blue or gold 
stain for axis-cylinders, can be applied to fresh tissues only. 

Others, like the various amyloid reactions, can be obtained 
with fresh or hardened tissues. Most of the micro-chemical 
reactions, however, can be employed only with tissues which 
have been properly preserved. It is exceedingly important, 
therefore, that a tissue-element be so fixed and hardened that 
its peculiar chemical properties be preserved intact, otherwise 
a differential stain for it is impossible. Each tissue-element 
is a law unto itself. For example, the peculiar chemical 
properties of red blood-globules depend on the presence in 
them of hemoglobin. As a differential stain of the red 
blood-globules depends on fixing this substance in them, it 
is necessary to find out the chemical properties of hemo- 
globin, such as the fact that it is soluble in water or dilute 
alcohol, but not in salt solution, and that it is fixed in the 
red blood-globules by heat, absolute alcohol and ether equal 
parts, corrosive sublimate, formaldehyde, bichromate of po- 
tassium, etc. 

While differential stains depend in part on the chemical 
properties of the tissue-elements, they also depend to a cer- 



HISTOLOGICAL METHODS. 307 

tain extent on the chemical properties of the staining re- 
agents and the decolorizers used. 

Some of the tissue-elements can be stained differentially in 
a number of ways, sometimes after one fixing agent, some- 
times after another. The simplest differential stains are those 
where certain tissue-elements stain directly in a given solu- 
tion after they have been properly fixed. Good examples 
are — Ehrlich's triple stain for certain protoplasmic granules 
in leucocytes, and the direct stain for elastic fibers with an 
acid alcoholic solution of orcein. 

Other differential stains depend on the property of certain 
elements to hold colors they have once taken up when 
treated with decolorizers. The best example of this is the 
tubercle bacillus, which holds certain stains through various 
acids, or aniline hydrochlorate, followed by alcohol, and, if 
necessary, by a contrast-stain. 

Still another varied group of elements (certain bacteria, 
fibrin, neuroglia-fibers, etc.) depends for a differential stain in 
part on changes produced in gentian- or methyl-violet by 
iodin, in part on the decolorizer employed for extracting the 
coloring reagent. 

Although the steps of the various staining methods differ 
considerably, they may be roughly arranged in the following 
order : 

1. Staining. 

2. Differentiating. 

3. Decolorizing. 

4. Dehydrating. 

5. Clearing. 

6. Mounting. 

Very often two or more of the steps are combined in one, 
as when aniline oil is used for decolorizing, dehydrating, and 
clearing sections stained for certain bacteria. Sometimes the 
staining process occupies more than one step, as in Weigert's 
myelin-sheath stain. In alum-hematoxylin the differentiating 
reagent, the excess of alum, is combined with the stain ; in 
Gram's method the differentiating reagent, iodin, forms a step 
by itself. 



308 PATHOLOGICAL TECHNIQUE. 

NUCLEAR STAINS. 

For general histological work few stains are more valua- 
ble or can be more highly recommended than alum-hema- 
toxylin, either alone or in contrast with eosin. Prop- 
erly made and used, the solution stains the nuclei sharply 
and of varying degrees of intensity, depending on the cha- 
racter of the cells. Besides the nuclei, however, it stains 
other tissue-elements in delicate shades of blue, so that they 
are readily visible, and thus more or less differentiated from 
those structures which fail to stain. 

Of the carmine stains, lithium carmine, followed by picric 
acid, will be found the most brilliant, generally useful, and 
permanent. 

Safranin gives, perhaps, the most permanent stain of any 
of the basic aniline dyes, and confines itself very sharply to 
the nuclei. It is much used after certain fixing reagents, such 
as Flemming's and Hermann's solutions. Eosin, followed by 
methylene-blue, gives beautiful results, especially when 
Unna's alkaline solution of methylene-blue is used. The 
advantages of this solution are that it stains readily tissues 
hardened in Zenker's fluid and brings out nuclei and nuclear 
figures with great sharpness, while at the same time it stains 
the protoplasm of certain cells so that they are easily dis- 
tinguished from other cells. The Heidenhain-Biondi triple 
stain is useful after fixation in corrosive sublimate, but can- 
not be employed with celloidin sections, so that its field is 
limited. The other aniline dyes are used on occasion or for 
some definite purpose, but not so generally as those men- 
tioned above. 

Alum-hematoxylin Stains. — Most alum-hematoxylin 
solutions will over-stain if the sections are left too long in 
them. The proper time required depends on the fixing re- 
agent used and on the degree of ripeness of the staining 
solution. It is therefore advisable to wash a section in water 
occasionally and decide from the color it has acquired if it 
be sufficiently stained, or to mount it in water on a slide and 
examine with the low power of the microscope. 



HISTOLOGICAL METHODS. 309 

The best results are obtained with alum-hematoxylin solu- 
tions by staining sections just deeply enough, washing them 
thoroughly in several changes of water, and leaving them in 
a large dish of water over night. This thorough washing is 
done to rid the tissues of every trace of alum or of acid, so 
that the color will become a clear blue and will keep in- 
definitely. 

Many microscopists prefer to stain deeply and diffusely in 
an old, quickly-staining alum-hematoxylin solution, and then 
to employ a decolorizer. The agents most used for the pur- 
pose are alum (1 per cent, aqueous solution for one to two 
hours), hydrochloric acid ( ^ to J per cent, aqueous solution, 
or even the ordinary acid alcohol), and acetic acid (1 to 3 per 
cent, solution) for a few seconds only. After being suf- 
ficiently decolorized the sections must be thoroughly washed 
in water, preferably for a number of hours, otherwise the 
stain will fade. The objection to this method is that a pure 
nuclear stain only is obtained, because the acid removes the 
color completely from all the rest of the tissue. Under cer- 
tain circumstances, as when hematoxylin is used as a con- 
trast-stain to fuchsin in staining for tubercle bacilli, such a 
sharp limitation to the nuclei is desirable. 

Alum-hematoxylin stains well and quickly tissues hard- 
ened in alcohol, in corrosive sublimate, and in picric acid. 
It stains much more slowly tissues hardened in solutions 
containing chrome salts, such as Zenker's and Miiller's 
fluids. 

For counter-staining eosin will usually be found to give 
the most beautiful contrast, although picric acid, Van 
Gieson's mixture, and neutral carmine are often of service. 

A good alum-hematoxylin solution should have a bluish 
or purplish color, and should stain celloidin very faintly or 
not at all. 

Aqueous Alum-hematoxylin; Delafield's Hema- 
toxylin; Ehrlich's Acid Hematoxylin (see pages 281 
and 282). 

1 . Stain in one of the above solutions two, five, or thirty 
minutes, or sometimes even lonsrer. 



3IO PATHOLOGICAL TECHNIQUE. 

2. Wash in several changes of water, and then leave sec- 
tions, if possible, for several hours or over night in a large 
dish of water ; or better still, wash in running tap water for 
ten to thirty minutes. 

3. Contrast-stain, usually an aqueous solution of eosin, 
ro to J per cent., for one to five minutes. 

*4. Alcohol, 95 per cent., two or three changes to dehydrate 
and to remove excess of contrast-stain. 

5. Clear in oleum origani cretici or in Dunham's oils-of- 
cloves-and-thyme mixture. 

6. Canada balsam. 

The staining of the nuclei by Ehlrich's alum-hematoxylin 
solution is not so sharp as that obtained by the simple aque- 
ous solution. 

The more customary method of using Delafield's alum- 
hematoxylin solution is to filter a few drops of it into a dish 
of water and to stain sections for a long time, even over 
night, with the very dilute solution thus obtained. It is 
sometimes advisable to use the aqueous solution in the same 
way. 

Mayers Hemalum (see page 283). — 1. Stain three to 
five minutes or longer. 

2. Wash out in I per cent, alum solution until the stain is 
precise. 

3. Wash thoroughly in several changes of water. 

4. Alcohol, 95 per cent. 

5. Oleum origani cretici. 

6. Canada balsam. 

The staining is rather diffuse, so that it has to be washed 
out to some extent with alum-water. Mayer's acid hemalum 
is more precise, and usually does not need to be decolorized, 
so that the second step can be omitted. 

Hemalum is used for staining tissues in bulk. Twenty- 
four hours are required for large pieces. 

Heidenhain's Hematoxylin Stain. — 1. Stain twenty- 
four to forty-eight hours in a simple \ per cent, aqueous 
solution of hematoxylin dissolved by the aid of heat. 

2. Transfer the sections directly to a J per cent, aqueous 



HISTOLOGICAL METHODS. 3II 

solution of simple chromate of potassium for twenty-four to 
forty-eight hours, changing the solution frequently until no 
more color is given off by the sections. 

3. Wash thoroughly in water. 

4. Alcohol. 

5. Oil. 

6. Canada balsam. 

Heidenhain's Iron Hematoxylin, — This staining 
method is particularly useful for the demonstration of the 
centrosome, but also stains nuclei and a variety of other 
structures, according to the degree of differentiation. 

1. Fix in corrosive sublimate, Zenker's fluid, or alcohol. 

2. Stain very thin paraffin sections (not over 5 to 6/2 
thick) in a 2.5 per cent, solution of the violet iron alum 
(sulphate of iron and ammonium) for three to twelve hours. 
The sections should be placed vertical in the solution, so 
that no precipitate may fall on them. 

3. Wash off quickly in water. 

4. Stain in a 0.5 per cent, ripened alcoholic solution of 
hematoxylin for twelve to thirty-six hours. 

5. Wash off in water. 

6. Differentiate in the iron-alum solution, controlling the 
results under the microscope. The section should be washed 
off before each examination in a large dish of tap water, 
which immediately stops the decolorization. 

7. Wash in running water for a quarter of an hour. 

8. Alcohol, xylol, xylol balsam. 

A counterstain with Bordeaux R. before, or with rubin S. 
after, the iron stain is sometimes useful. 

Mallory's Chlorid of Iron Hematoxylin. 1 — The 
results which can be obtained by this method are equally 
quick and satisfactory after all of the usual fixing reagents 
except, perhaps, formaldehyde. 

Celloidin or paraffin can be employed for embedding. 

1. Stain sections on the slide for three to five minutes in 
a 10 per cent, aqueous solution of ferric chlorid. 

2. Drain and blot the sections ; then pour over them a 

1 Mallory : The Journal of Experimental Medicine, 1900, v., iS. 



312 PATHOLOGICAL TECHNIQUE. 

few drops of a freshly prepared I per cent, aqueous solution 
of hematoxylin. If all of the hematoxylin is precipitated by 
the excess of ferric chlorid, pour off the solution and add a 
fresh supply. In three to five minutes the sections will be 
colored a dark bluish-black. 

3. Wash in water. 

4. Decolorize and differentiate in a ^ per cent, aqueous 
solution of ferric chlorid. The sections should be kept con- 
stantly moving in the solution. The differentiation will be 
complete in a few seconds to one or more minutes. 

5. Wash in water. 

6. Dehydrate in alcohol. 

7. Clear in oleum origani cretici. 

8. Xylol balsam. 

In the above directions definite strengths have been 
assigned to the solutions, but they may vary greatly with- 
out affecting the result. The important point is to get the 
sections stained deeply, and then to decolorize slowly. The 
differentiation can be stopped at any moment by transferring 
the sections to water. Sometimes it is advisable to examine 
the sections under the microscope to see if enough color has 
been extracted. 

The strength of the hematoxylin solution is unimportant ; 
it is simply necessary to have enough hematoxylin to com- 
bine with all of the iron in and on the section. The sim- 
plest way is to dissolve by the aid of heat a pinch of the 
crystals in a few cubic centimeters of water. A little ex- 
perience will determine about how much is needed. If a 
solution of hematoxylin more than one or two days old is 
used, the color obtained is grayish-blue, and not so bright. 

This method gives a sharp, permanent, dark-blue stain to 
nuclei ; it also stains fibrin of a grayish to dark-blue color ; 
if the decolorization is not carried too far, the contractile ele- 
ments of striated muscle are brought out very sharply. In 
Zenker preparations the red globules appear of a greenish - 
gray color. Connective tissue is tinted a pale yellow. The 
nucleus of the amoeba coli stains sharply by this method. 

Carmine Stains. — The ordinary carmine solutions give 



HISTOLOGICAL METHODS. 313 

good nuclear stains, but of the finer details in a specimen 
they bring out much less than a direct alum-hematoxylin 
stain. They are much less used now than formerly, except 
as contrast-stains to bacteria and to fibrin in the methods of 
Gram and Weigert, for which purpose lithium carmine will 
usually give the best results. 

Alum Carmine ; Alum Cochineal (see pages 285 and 
286).— 1. Water. 

2. Stain in either of the above solutions for five to twenty 
minutes. 

3. Wash thoroughly in water. 

4. Alcohol, 95 per cent. 

5. Oleum origani cretici. 

6. Canada balsam. 

Over-staining does not occur. The solutions cannot be 
recommended for tissues which stain with difficulty. When 
used for staining in bulk, twenty-four to forty-eight hours are 
required. 

Lithium Carmine (see page 286). — 1. Water. 

2. Stain two to five minutes. 

3. Transfer directly to acid alcohol, one or more changes 
for several minutes or more, until the sections are well differ- 
entiated. 

4. Wash in water. 

5. Alcohol, 95 per cent. 

6. Oleum origani cretici. 

7. Canada balsam. 

This method gives an intense and permanent bright-red 
nuclear stain. Over-staining is impossible. A trace of 
picric acid added to the alcohol used for dehydration 
affords a beautiful contrast-stain. 

Aniline Dyes as Nuclear Stains.— Any of the basic 
aniline dyes may be used as nuclear stains after the following 
general method : 

1. Stain paraffin sections in a strong solution of the dye 
preferred in water or in dilute alcohol for five to thirty 
minutes. 

2. Wash in water. 



3 14 PATHOLOGICAL TECHNIQUE. 

3. Dehydrate in absolute alcohol. 

4. Clear in xylol. 

5. Xylol balsam. 

With celloidin sections use 95 per cent, alcohol, blot with 
filter paper, and clear in xylol. 

As a matter of fact, however, certain dyes and certain 
solutions are generally used in preference to the others. 
Most of the colors are more or less affected by all clearing 
reagents except xylol. With paraffin sections and those 
from which the celloidin has been removed it is very 
easy to dehydrate in absolute alcohol and to clear in 
xylol. With celloidin sections, however, this is impossible, 
because the absolute alcohol will dissolve out the celloi- 
din, and this is usually not desirable. For celloidin sec- 
tions, therefore, blot with filter paper, and then pour on 
xylol ; repeat the blotting, followed by xylol, two or three 
times until the specimen is perfectly clear. Mount in xylol 
balsam. 

In washing out the excess of color it is sometimes found 
advantageous to acidulate very slightly either the water or 
the first alcohol with acetic or hydrochloric acid. This pro- 
cess, if not carried too far, tends to make the nuclear stain 
sharper. 

Safranin is one of the very best nuclear-staining aniline 
dyes. Tissues may be hardened in alcohol, corrosive subli- 
mate, Flemming's, Hermann's, or Zenker's fluids. Any 
one of the solutions of safranin given on page 290 may 
be used. 

1. Stain paraffin sections two to five minutes to twenty- 
four hours according to the staining solution and fixing re- 
agent used. 

2. Wash in water. 

3. Absolute alcohol, several changes, until the section 
appears properly differentiated. 

4. Xylol. 

5. Xylol balsam. 

For celloidin sections dehydrate in 95 per cent, alcohol, 
clear in bergamot or origanum oil, and wash out in xylol. 



HISTOLOGICAL METHODS. 315 

To render the stain more precise a few drops of acid alcohol 
are sometimes added to the first alcohol. 

The Eosin and Methylene-blue Stain. — This stain, used 
on paraffin sections of tissues fixed in Zenker's fluid, can be 
recommended as the very best general stain yet devised. It 
is a sharp nuclear stain, and, at the same time, brings out 
with a great deal of differentiation all the various other 
structures in the different tissues. It has been in constant 
use for many years as the routine stain for all tissues in the 
pathological laboratories of the Harvard Medical School 
and Boston City Hospital. 

Fix in Zenker's fluid or in corrosive sublimate. Alcohol 
and formaldehyde are not nearly so good. 

1. Stain paraffin sections in a 5 to 10 per cent, aqueous 
solution of eosin for twenty minutes or longer. Sometimes 
it is advisable to get a deeper eosin stain by placing the sec- 
tions in the paraffin oven for fifteen to twenty minutes. 

2. Wash in water to get rid of excess of eosin. 

3. Stain in Unna's alkaline methylene-blue solution (see 
page 288), diluted 1-4 or 5 with water, for ten to fifteen 
minutes. 

4. Wash in water. 

5. Differentiate and dehydrate in a dish of 95 per cent, 
alcohol, keeping the section in constant motion, so that the 
decolorization shall be uniform. Control the result under 
the microscope. When the pink color has returned to the 
section and the nuclei are still a deep blue, finish the dehy- 
dration quickly with absolute alcohol. 

6. Xylol. 

7. Xylol balsam. 

For celloidin sections use 95 per cent, alcohol, blot, and 
pour on xylol ; repeat the last two steps until the specimen 
is clear. 

It is important to get a deep stain with eosin, because the 
methylene-blue washes it out to a considerable extent. The 
eosin must be used first, because methylene-blue is readily 
soluble in an aqueous solution of eosin, and therefore is 
quickly extracted if the eosin is used after it, while on the 



316 PATHOLOGICAL TECHNIQUE. 

other hand eosin is very slightly soluble in an aqueous solu- 
tion of methylene-blue which is precipitated by any excess 
of eosin. 

Diffuse or contrast-Stains are useful to make promi- 
nent certain of the tissue-elements left uncolored by the 
nuclear stain. A greater richness of detail is obtained with 
diffuse stains if, after rather deep staining, the sections be 
washed out for some time in alcohol, because certain struc- 
tures possess a greater affinity than others for certain diffuse 
stains, and by holding them are brought out sharply. 

Of the diffuse stains, eosin, picric acid, and acid-fuchsin in 
Van Gieson's mixture are the ones most frequently em- 
ployed. 

Eosin is most frequently used as a contrast to alum-hema- 
toxylin stains, but is often serviceable with alum-cochineal, 
methylene-blue, gentian-violet, etc. It brings out particu- 
larly well red blood-globules and smooth and striated muscle- 
fibers. The strength of the solutions used after hematoxy- 
lin varies from -^ to \ per cent, according to the tissue and 
the fixative used. Zenker's preparations stain intensely in 
eosin, so that for them a very dilute solution is advisable. 
When desired as a contrast-stain to basic aniline dyes, eosin 
should be used first in a 5 or even 10 per cent, solution, 
because otherwise it is likely to be washed out by the 
nuclear stain. 

Picric acid is used for contrast with the carmine stains, 
more rarely with alum-hematoxylin. Striated muscle-fibers 
and cornified epithelium are rendered especially prominent 
by it. To stain with picric acid it is only necessary to add a 
few drops of a saturated aqueous solution to a dish of water, 
or of a saturated alcoholic solution to a little alcohol, and 
allow sections to remain in the solution for a few seconds. 

Van (Meson's stain (see p. 291), a mixture of picric acid 
and acid fuchsin, is excellent as a contrast-stain to alum- 
hematoxylin, especially when it is desirable to render promi- 
nent connective-tissue fibrillar or certain pathological prod- 
ucts. The nuclear stain with alum-hematoxylin must be 



HISTOLOGICAL METHODS. 317 

rather deep, because the picric acid to some extent extracts 
or overpowers it. 

1. Stain deeply in alum-hematoxylin. 

2. Wash in water. 

3. Stain in Van Gieson's solution three to five minutes. 

4. Wash in water and dehydrate directly in 

5. Alcohol, 95 per cent. 

6. Oleum origani cretici. 

7. Canada balsam. 

Neutral Carmine (see page 286). — Neutral carmine is a 
diffuse stain, and is employed more especially for the central 
nervous system and for bone. 

Filter one or two drops of the solution into 20 c.c. of dis- 
tilled water, and leave the sections in the dilute solution over 
night. It is advisable to place a piece of filter-paper on the 
bottom of the dish for the sections to rest on, otherwise they 
may be stained on the upper side only. In double stains 
with hematoxylin and carmine the sections should be stained 
first in the hematoxylin and then thoroughly washed in water 
for six to twelve hours before they are stained in the carmine. 
After the carmine they are again to be thoroughly washed in 
water. 

Combination Stains. — Biondi-Heidenhain Stain (see 
p. 292). — Tissues must be hardened in corrosive sublimate. 

1. Stain paraffin sections six to twenty-four hours with the 
dilute solution. 

2. Wash out a little in 90 per cent, alcohol. 

3. Dehydrate in absolute alcohol. 

4. Xylol. 

5. Canada balsam. 

It is important to place the sections directly from the 
staining fluid into the alcohol, because water washes out the 
methyl-green almost instantly. 

Staining" in Mass. — The staining of tissues in mass is a 
procedure much less employed in pathological than in nor- 
mal histology, but still occasionally useful. For patholog- 
ical tissues a variety of stains is generally necessary. It is 
therefore much better to make a series after one of the 



318 PATHOLOGICAL TECHNIQUE. 

methods described, and then to stain the sections in what- 
ever way seems best. 

For staining in bulk only a limited number of solutions 
are available — either those, like alum-carmine and alum- 
cochineal, which do not stain beyond a certain point, or 
those, like lithium and borax-carmine and Heidenhain's 
hematoxylin, which may be decolorized so as to leave only 
the nuclei stained, The process of staining differs from that 
for sections only in the length of time required for each step. 
Tissues \ cm. thick will need from one to two days in the 
staining solution. 

MITOSIS. 

For the study of karyomitosis it is important that the 
tissue be perfectly fresh — that is, just removed from a living 
animal or from one just dead — and that it be fixed in a 
suitable reagent as quickly as possible. The best results 
cannot be obtained with tissues put into a hardening fluid 
over half an hour after removal from a living animal. On 
the other hand, mitotic figures can be demonstrated in tissues 
which have been dead for some time (twenty-four hours or 
more) before being put into a fixing reagent, but the details 
of the figures are not so perfect as those in perfectly fresh 
tissues, and the figures are not so numerous, because some 
of them have completed their changes and can no longer be 
recognized. It is therefore evident that mitosis can be 
studied much better in tissues from the lower animals, or 
in tissues removed by operation from the human body, 
than in the organs and tissues removed at post-mortem 
examinations. 

The choice of fixing reagents for the study of mitotic 
figures is important. The figures can often be demonstrated 
after hardening in alcohol or even in Miiller's fluid, but for 
their careful study quicker and more perfect fixing reagents 
must be used. Nearly all of the reagents employed pene- 
trate slowly, so that it is absolutely necessary for the best 
results that the tissue to be hardened be cut into very thin 
slices, rarely over 4 mm. in thickness and preferably not over 



HISTOLOGICAL METHODS. 319 

2 mm. The amount of fixing reagent used should always be 
at least ten to fifteen times as great as the volume of the 
tissue, and should be changed if it becomes cloudy. 
The most important fixing reagents are — 

1. Flemming's solution. 

2. Hermann's solution. 

3. Pianese's solution. 

4. Zenker's fluid. 

5. Corrosive sublimate. 

6. Orth's fluid. 

The first three solutions penetrate with much difficulty, so 
that tissues placed in them should be especially thin. The 
most generally useful stain for mitosis is probably safranin. 
The time of staining varies with the solution used. Babes' 
is the quickest. The mitotic figures should be stained 
deeply : then, when treated with alcohol slightly acidulated 
with hydrochloric acid, they will retain the color, while the 
resting nuclei will yield up most of theirs and become very 
pale or even colorless. In consequence of this intense stain 
mitotic figures can then be very readily found. 

Directions for Staining Karyomitotic Figures with 
Safranin. — I. Stain paraffin sections five minutes to twenty- 
four hours, according to solution used. 

2. Wash in water. 

3. Wash in 95 per cent, alcohol to which are added a few 
drops of acid alcohol. 

4. Wash in pure 95 per cent, alcohol, followed by absolute 
alcohol. 

5. Xylol. 

6. Xylol balsam. 

For celloidin sections dehydrate in 95 per cent, alcohol, 
blot, and pour on xylol ; repeat the last two steps until the 
specimen is clear. Safranin can be used after any of the 
above fixing reagents. 

Other useful stains are carbol-fuchsin and aniline-gentian- 
violet, used in the same way as the safranin. The Gram- 
Weigert method gives good results after Flemming's solu- 
tion. 



320 PATHOLOGICAL TECHNIQUE. 

After fixing in corrosive sublimate mitotic figures can be 
demonstrated by the Biondi-Heidenhain solution, which 
stains resting nuclei blue-violet and mitotic figures green. 
After Pianese's solution his special staining mixtures should 
be used (see page 293). His methods are said to give 
beautiful results. 



SPECIAL STAINS FOR CERTAIN TISSUE=ELEMENTS 
OTHER THAN NUCLEI. 

MASTZELLEN. 

Mastzellen are found in the connective tissue, more 
especially in chronic inflammatory processes. Their proto- 
plasmic granules stain intensely like bacteria with the basic 
aniline dyes. Several methods of staining the granules are 
given. With Unna's stains for plasma-cells a differential 
color-stain is obtained for the granules of the mastzellen. 

Ehrlich's Method. — A. General Stain. — Harden in alcohol. 

1. Stain with a saturated aqueous solution of dahlia. 

2. Wash out with acidified water. 

3. Dehydrate in alcohol ; clear and mount in Canada 
balsam. 

B. Specific Stain. — Only the protoplasmic granules are 
stained. Harden in alcohol. 

1. Stain twelve hours in — 

Absolute alcohol, 50 c.c. 

Water, 100 " 

Glacial acetic acid, 12.5 " 

Dahlia, q. s., so that the 

solution is almost saturated. 

2. Wash out in alcohol, clear, and mount. 

C. Ehrlich- Westphal Method. — Nuclei red ; granules blue. 
Harden at least a week in alcohol. 



HISTOLOGICAL METHODS. 32 I 

I. Stain in the following solution twenty-four hours : 

Alum-carmine solution, 200 ; 

Saturated solution of dahlia in absolute alcohol, 200 ; 

Glycerin, 100; 

Glacial acetic acid, 20. 

(Stir repeatedly, then allow the mixture to stand for some 
time.) 

2. Decolorize for twenty-four hours in absolute alcohol. 

3. Oil, Canada balsam. 

Unna's Isolated Stains for Mastzellen. — Harden in alco- 
hol. Nuclei blue ; protoplasmic granules of " Mastzellen " red. 

A. — 1. Stain in polychrome methylene-blue solution, plus 
a little alum, for three hours to over-night. 

2. Wash in water. 

3. Absolute alcohol, oil of bergamot, balsam. 

B. — 1. Stain in polychrome methylene-blue solution one- 
quarter of an hour. 

2. Wash in water. 

3. Decolorize in glycerin-ether mixture for five to ten 
minutes. 

4 Wash a long time in water. 
5. Absolute alcohol, oil, balsam. 



PLASMA=CELLS. 

These are certain cells, much studied by Unna, which are 
very abundant in subacute and chronic pathological pro- 
cesses, and which are characterized by protoplasm which 
stains quite deeply in alkaline methylene-blue solutions. 
The two methods best suited for their demonstration furnish 
at the same time a differential color-stain for mastzellen. 
The granules of the latter are stained red, the plasma-cells 
are stained blue. 

Unna's Differential Stains for Plasma-cells and Mast- 
zellen. — Harden tissues in absolute alcohol. 

A. — I. Stain paraffin sections in polychrome methylene- 
blue one-quarter of an hour to over-night. 

2. Decolorize in a small dish of water, to which are added 

a few drops of glycerin-ether mixture. 
21 



322 PATHOLOGICAL TECHNIQUE. 

3. Wash thoroughly in water. 

4. Absolute alcohol, xylol, balsam. 

B. — 1. Stain in polychrome methylene-blue solution five 
to fifteen minutes. 

2. Wash in water. 

3. Decolorize and dehydrate in a \ per cent, alcoholic 
solution of neutral orcein (about fifteen minutes). 

4. Absolute alcohol, xylol, balsam. 

CONNECTIVE=TISSUE FIBRILL/E AND RETICULUM. 

Several methods are available for the demonstration of 
connective fibrillar and reticulum. The simplest is by means 
of Van Gieson's picric acid and acid-fuchsin solution, but it 
is applicable to the coarser fibers only. With Ribbert's 
method contrast stains are incompatible. The stain with 
aniline blue is believed to be better than any yet proposed, 
but is limited to tissues hardened in corrosive sublimate 
solution or in Zenker's fluid. 

A. Mallory's Aniline Blue Stain. 1 — The following method 
is not absolutely differential because, besides connective-tis- 
sue fibrillse and reticulum, it also stains certain hyaline sub- 
stances, but these latter usually are so different morpho- 
logically that confusion cannot arise. The method is also 
useful for the study of fibrin, fibroglia fibrils, smooth and 
striated muscle-fibers, and amyloid. 

1. Fix in Zenker's fluid. 

2. Imbed in celloidin or paraffin. 

3. Stain sections in a -^ per cent, aqueous solution of acid 
fuchsin for five minutes or longer. 

4. Transfer directly to the following solution and stain for 
twenty minutes or longer : 

Aniline blue soluble in water (Griibler), 0.5 ; 

Orange G (Griibler), 2.0; 
One per cent, aqueous solution of phos- 

phomolybdic acid, 100.0; 

1 Mai lory : The Journal of Experimental Medicine, 1 900, v., 15. 



HISTOLOGICAL METHODS. 323 

5. Wash and dehydrate in several changes of 95 per cent, 
alcohol. 

6. Clear in xylol or in oleum origani cretici. 

7. Xylol balsam. 

The fibrillar and reticulum of connective tissue, amyloid, 
mucus, and certain other hyaline substances stain blue ; 
nuclei, protoplasm, fibroglia fibrils, axis-cylinders, neuroglia- 
fibers, and fibrin red; red blood-globules and myelin-sheaths 
yellow ; elastic fibers pale pink or yellow. The various 
structures do not stain with equal intensity, so that certain 
ones are brought out with great sharpness. This is par- 
ticularly true of the fibrillar and reticulum of connective 
tissue, and of fibrin and smooth and striated muscle-fibers. 

If it is desired to bring out the connective tissue as 
sharply as possible, omit the staining with acid fuchsin. 
Then the nuclei and protoplasm stain yellow, and the blue 
fibrillar and reticulum stand out more prominently. 

B. Van Gieson's Stain. — The proportions given are those 
recommended by Freeborn. Occasionally it will be found 
necessary to increase the proportion of the acid fuchsin. 

1. Harden in chrome salts or in corrosive sublimate. The 
results after alcohol are not so good. 

2. Stain deeply in alum-hematoxylin. 

3. Wash in water. 

4. Stain for three to five minutes in 

1 per cent, aqueous solution of acid fuchsin, 5 c.c. 
Saturated aqueous solution of picric acid, 100 " 

5. Dehydrate in 95 per cent, alcohol. 

6. Oleum origani cretici. 

7. Canada balsam. 

C. Unna's Orcein Stain. — 1. Harden in alcohol. 

2. Stain in the concentrated solution of polychrome 
methylene-blue five minutes. 

3. Wash in water. 

4. Decolorize, differentiate, and stain in a 1 per cent, solu- 
tion of orcein in absolute alcohol fifteen minutes. 

5. Wash in absolute alcohol. 



324 PATHOLOGICAL TECHNIQUE. 

6. Oil of bergamot. 

7. Balsam. 

Nuclei, dark blue ; protoplasm, pale blue; elastic and con- 
nective-tissue fibers, deep orcein red ; smooth muscle-fibers, 
bluish ; mastzellen granules, red ; protoplasm of plasma- 
cells, deep blue. 

D. Mall's Differential Method for Reticulum. 1 — 1. Digest 
frozen sections of fresh tissue, 40 to 80 p. thick, for twenty- 
four hours in the following solution : 

Parke, Davis & Co.'s pancreatin, 5 grams ; 

Bicarbonate of sodium, 10 " 

Water, 100 c.c, 

2. Wash carefully in clean water. 

3. Place sections in a test-tube half full of water, and 
shake thoroughly in order to remove all the cellular debris. 

4. Spread out on slide, and allow to dry. 

5. Allow a few drops of the following solution to dry on 
surface : 

Picric acid, 10 grams ; 

Absolute alcohol, 33 c.c. ; 

Water, 300 " 

6. Stain for about half an hour in the following solution : 

Acid fuchsin, 10 grams ; 

Absolute alcohol, 33 c.c; 

Water, 66 " 

7. Wash in the picric acid solution for a moment. 

8. Alcohol, xylol, balsam. 

FIBROQLIA FIBRILS.2 

Connective-tissue cells produce, in addition to reticulum, 
the fibrils of white fibrous tissue, and elastic fibrils, a fourth 
variety of fibrils, which bear the same relation to the con- 

1 Mall : Johns Hopkins Hospital Reports, 1 896, i., 1 7 1. 

2 Mallory : "A Hitherto Undescribed Fibrillar Substance Produced by 
Connective-tissue Cells," Journal of Medical Research, 1903, vol. x. 



HISTOLOGICAL METHODS. $2$ 

nective-tissue cells that neuroglia fibrils bear to neuroglia 
cells. Fibrils which stain by this same method are present 
also in the true basement membrane of the coil-glands of 
the skin, of the glands of the breast, and many tumors 
derived from them, of the tubules of the kidney, and beneath 
the endothelium of arteries and veins. The stroma of a 
more or less scirrhous carcinoma of the breast furnishes 
excellent material for their study. 

Mallory's Differential Stain. — I. Fix in Zenker's fluid. 
The tissue should be as fresh as possible, and cut into thiu 
sections (2 to 4 mm. thick) for the best results. 

2. Stain celloidin or paraffin sections in a 1 per cent, 
aqueous solution of acid fuchsin overnight in the cold, or 
twenty to thirty minutes in the paraffin oven (56 C). 

3. Wash quickly in water (not over five seconds). Water 
extracts acid fuchsin very rapidly. 

4. Differentiate in a 0.25 per cent, aqueous solution of 
permanganate of potassium for twenty to forty seconds. 
This step must not be prolonged beyond the exact time 
needed or the section will be decolorized. 

5. Wash quickly in water (not over five seconds). 

6. Dehydrate in alcohol. 

7. Clear in oleum origini craetici or in xylol. 

8. Mount in xylol balsam. 

While not an absolutely differential stain for these fibrils, 
the method, for the most part at least, is perfectly satisfac- 
tory. It stains intensely red, not only these fibrils and the 
cell nuclei, but also fibrin, the contractile elements of striated 
muscle-cells, the coarse, differentially staining fibrils of 
smooth muscle-cells, neuroglia fibers, and the cuticular 
surfaces of epithelial cells. Ordinary connective-tissue fibrils 
appear from brownish-yellow to colorless ; elastic fibrils, 
unless degenerated, are bright yellow. 

These fibrils can also be stained by several other methods. 
The most reliable is, perhaps, phosphotungstic acid hema- 
toxylin after fixation in Zenker's fluid. 

1. Place sections in a J per cent, aqueous solution of per- 
manganate of potassium ten to twenty minutes. 



326 PATHOLOGICAL TECHNIQUE. 

2. Wash off in water. 

3. 5 per cent, aqueous solution of oxalic acid one to two 
hours. 

4. Wash thoroughly in several changes of water. 

5. Stain in phosphotungstic acid hematoxylin twenty- 
four to forty-eight hours. 

6. Wash off in water. 

7. Alcohol, xylol, balsam. 

In sections stained by the aniline-blue connective tissue 
stain these fibrils appear bright red. They can also be 
demonstrated by either of the iron-hematoxylin methods if 
the differentiation is not carried too far. 

ELASTIC FIBERS. 

Elastic fibers are not affected by dilute caustic soda or 
potash, or by acids. These reagents are often used, there- 
fore, to demonstrate elastic fibers in the fresh condition, as, 
for example, in sputum, because they render them prominent 
by clearing or destroying the other tissues. The fibers show 
a marked affinity for osmic acid, staining with greater rapid- 
ity than most other tissue-elements. 

For bringing out elastic fibers in sections of hardened 
tissues there are two excellent differential stains, of which 
the first, Weigert's, is particularly recommended for the sim- 
plicity of the method and the sharpness and intensity of the 
picture it gives. 

A. Weig-ert's Stain for Elastic Fibers. 1 — Fixation in 
alcohol or formaldehyde preferable, but other fixing reagents 
give good results. Imbed in celloidin or paraffin. 

1. Stain sections twenty minutes to one hour in the fol- 
lowing solution : 

Fuchsin, 2 ; 

Resorcin, 4 ; 

Water, 200. 

Boil the solution in a porcelain dish ; when briskly boil- 
ing add 25 c.c. of liquor ferri sesquichlorati ; stir and boil 

1 Weigert : Centralblatt fur allg. Pathologie, 1898, ix., 289. 



HISTOLOGICAL METHODS. 327 

for two to five minutes. A precipitate forms. Cool and 
filter. The filtrate is thrown away. The precipitate remains 
on the filter-paper until all the water has drained away or 
until the precipitate has thoroughly dried. Then return 
filter and precipitate to the porcelain dish, which should be 
dry, but which should contain whatever part of the precipi- 
tate remained sticking to it. Add 200 c.c. of 95 per cent, 
alcohol, and boil. Stir constantly, and fish out the filter-paper 
as the precipitate is dissolved off. Cool ; filter ; add alcohol 
to make up the 200 c.c. Add 4 c.c. of hydrochloric acid. 
1 2. Wash off in alcohol. 

3. Blot with filter-paper, and add xylol quickly ; repeat 
the blotting, followed by xylol, two or three times until the 
section is perfectly cleared. 

4. Xylol balsam. 

Sections can be stained for several hours. If the rest of 
the tissue is overstained, differentiate in acid alcohol ; if the 
sections are too deeply stained, the color cannot be washed 
out. Diffuse staining can be avoided by diluting the stain. 
The elastic fibers appear dark blue, almost black, on a clear 
background. The nuclei can be stained red with carmine 
before or after the staining of the fibers. 

The solution keeps for months. 

If it be desired to keep sections for some time before 
mounting, wash them in alcohol and place in water. 

B. Unna's Orcein Method for Elastic Fibers. — Unna's 
latest method of using orcein is as follows, and can be highly 
recommended : 

1. Stain sections in the following solution : 

Orcein (Grubler), 1 ; 

Hydrochloric acid, I ; 

Absolute alcohol, 100. 

Place the sections in a dish and pour over them enough 
of the solution to cover them. Warm gently in an incu- 
bator or over a small flame for ten to fifteen minutes until 
the solution thickens, or leave in the solution at room- 
temperature overnight. 



328 PATHOLOGICAL TECHNIQUE. 

2. Wash off thoroughly in dilute alcohol (70 per cent.). 

3. Wash in water to get rid of all the acid and to fix the 
color. 

4. Alcohol. 

5. Oil. 

6. Balsam. 

The washing in water is not absolutely essential. 

Elastic fibers are stained of a deep silky-brown color, con- 
nective tissue a pale brown. If it is desirable to have only 
the elastic fibers stained, wash for a few seconds in 1 per 
cent, hydrochloric-acid alcohol before washing in water. 
The nuclei can be brought out by staining in Unna's poly- 
chrome methylene-blue solution after washing the sections 
in water. 

SMOOTH AND STRIATED MUSCLE=CELLS. 

Smooth and Striated Muscle-cells. — For the demon- 
stration of muscle-cells double stains, such as alum-hema- 
toxylin and eosin or eosin and methylene-blue, are sufficient. 
For certain purposes, however, the aniline-blue connective- 
tissue stain is much to be preferred. For the demonstration 
of the coarse, differentially staining myoglia fibrils of smooth 
muscle-cells three methods are available, but all of them 
stain also the fibroglia fibrils of connective-tissue cells. (See 
p. 322.) 

1. Heidenhain's iron-hematoxylin stain is useful, especially 
for cross-sections of the fibrils. (See p. 311.) 

2. Benda's Stain for Myoglia Fibrils. 1 — 1. Fix fresh 
material in Zenker's fluid for twenty-four hours. 

2. Wash for a number of hours in water. 

3. Make frozen sections. 

4. Place sections in a 0.5 per cent, solution of chromic 
acid for twenty-four hours. 

5. Wash off in water. 

6. Place in a 0.25 per cent, solution of permanganate of 
potassium for about three minutes. 

1 Erganzungsheft zum XXI. Band, 1 902, des Anatomiscken Anzeigers> 
p. 214. 



HISTOLOGICAL METHODS. 329 

7. Wash off in water. 

8. Place in Pal's mixture of sulphite of sodium and oxalic 
acid for five minutes. 

9. Wash off in water; take up section on slide. 

10. Cover with the following solution : 

Crystal-violet, saturated solution in 70 per 

cent, alcohol, 1 part; 

Acid alcohol, 1 " 

Aniline-water, 2 parts. 

11. Blot with filter-paper. 

12. Cover with dilute Lugol's solution. 

1 3. Blot with filter-paper ; dry. 

14. Differentiate in aniline oil and xylol, equal parts. 

15. Xylol; xylol balsam. 

3. Mallory's differential stain for fibrog-lia fibrils is 
much simpler than the above method of Benda's, and gives 
equally good results. (See p. 322.) 

THE CENTRAL NERVOUS SYSTEM. 

In the preservation of the central nervous system the 
special structures which require consideration are the gan- 
glion-cells, including both the dendritic and the axis-cylinder 
processes, the myelin-sheaths, and the neuroglia-fibers. No 
one fixing reagent is suited for the best preservation of all 
of them, unless possibly it be formaldehyde. 

The main fixing fluids for the nervous system until within 
a very short time have been various solutions of the chrome 
salts, particularly of bichromate of potassium, either alone 
or in combination with sulphate of sodium, as in the well- 
known Muller's fluid. The chief objections to the chrome 
salts as fixatives are that they penetrate and harden very 
slowly, and do not preserve properly either the ganglion- 
cells or the neuroglia-fibers. On the other hand, they prob- 
ably preserve the axis-cylinders as well as any reagent we 
yet know, and are invaluable for their property of enter- 
ing into some chemical combination with myelin, in con- 
sequence of which it is possible to obtain by the method 



330 PATHOLOGICAL TECHNIQUE. 

originated by Weigert a differential stain of the myelin- 
sheaths. 

The new fixing reagent, formaldehyde, seems likely to find 
its greatest use histologically as a fixative of the central 
nervous system. It penetrates and hardens up to a certain 
degree with great rapidity. It also preserves in certain struc- 
tures the special chemical properties on which certain differ- 
ential stains depend. Small pieces of nervous tissue are 
properly fixed in the standard solution (4 per cent, solution 
of formaldehyde gas) in four days. A whole brain will be 
so hardened in ten days to two weeks that thin serial sections 
can be made through it without fear of the slices altering 
their shape in the least. The process could undoubtedly 
be hastened by injecting the arteries. 

It must be borne in mind, however, that for most purposes 
formaldehyde must be followed by other reagents before the 
structures and their chemical properties preserved by it are 
properly fixed so that they will not be altered when trans- 
ferred to alcohol. In other words, formaldehyde may be 
looked upon as a very quick preliminary fixing reagent. 
The hardening of brains entire in it is not recommended, 
except in certain cases — for instance, of cysts, hemorrhages, 
or occasionally of tumors — where the gross lesions and the 
tracts or structures affected by them are of more importance 
than the finer histological changes. For the proper preser- 
vation of ganglion-cells and of neuroglia-fibers very small 
pieces must be taken and fixed by the special methods 
given ; but if the main object is to trace system-degenera- 
tions, much larger pieces, or even the whole brain, may be 
taken, because the myelin-sheaths change comparatively very 
slowly after death. 

The stains for the central nervous system may be divided 
into two classes — general and differential. For nearly all of 
them preliminary fixation in formaldehyde is advisable or 
possible. This renders the immediate preservation of ner- 
vous tissue very simple, and at the same time allows a variety 
of mordanting and staining methods to be used later. 

The staining of the various histological elements of the 



HIS TOL GICAL ME THODS. 3 3 1 

central nervous system and the fixing reagents best suited 
for each of them will be considered under the following 
headings : 

General Stains. 

{Protoplasmic granules ; 
Dendritic and axis-cylinder processes ; 
Axis-cylinders and their terminal processes. 
Stains for the myelin-sheath. 
Stains for the neuroglia-fibers. 

General Stains. — General stains include the ordinary 
nuclear stains, with or without a contrast-stain, and certain 
diffuse single or combined stains which color the nuclei, the 
cell-protoplasm, including to a varying extent the dendritic 
processes of the ganglion-cells, the axis-cylinders, and the 
neuroglia-fibers. The different stains vary somewhat in regard 
to the structures which they bring out most prominently. 

The best fixation for the general stains is, on the whole, 
that used for mordanting the myelin-sheaths ; in other words, 
formaldehyde combined with or followed by a chrome salt 
(see page 342). Occasionally the fixatives employed for 
other tissues are indicated. Alum-hematoxylin, followed by 
eosin, is always a useful stain. The eosin, if deep enough, 
brings out fairly well both the dendrites and the axis- 
cylinders. The basic aniline dyes, especially methylene-blue, 
find their greatest use in Nissl's method of staining the 
protoplasmic granules of the ganglion-cells. 

The various carmine solutions, particularly neutral, 
ammonia, and picro-carmine, have long been the favorite 
diffuse stains for the central nervous system, but the uncer- 
tainty of their action and the difficulty of always getting a 
good staining solution has gradually led to the introduction 
of more reliable methods. Of these, the simplest, quickest, 
and in many ways the most generally useful is — 

A. Van Gieson's Stain. — Although this mixture of acid 
fuchsin and picric acid may be made up in the way originally 
recommended, the following exact proportions, given bv 
Freeborn for staining nervous tissues, will be found gener- 
ally preferable : 



332 PATHOLOGICAL TECHNIQUE. 

I per cent, aqueous solution of acid fuchsin, 15 c.c. ; 
Saturated aqueous solution of picric acid, 50 " 
Water, 50 " 

1. Stain sections first rather deeply in alum-hematoxylin. 

2. Wash in water. 

3. Stain in above solution three to five minutes. 

4. Dehydrate in alcohol. 

5. Oil, Canada balsam. 

The nuclei appear bluish red, the ganglion-cells and pro- 
cesses red, the axis-cylinders brownish-red, the myelin- 
sheaths yellow, the neuroglia-fibers orange red, connective- 
tissue fibrillar deep red. After certain reagents this solution 
will not give a sufficiently intense stain. In such cases a 
mixture of 1 part of a 1 per cent, solution of acid fuchsin to 
2 parts of a saturated solution of picric acid is recommended. 

B. Phosphotung-stic-acid hematoxylin (see page 284) 
will be found of much value as a general stain for the central 
nervous system if employed in the manner recommended 
for neuroglia-fibers after fixation by the method there given, 
because a greater differentiation of the various tissue-ele- 
ments is obtained than by any other method. Preliminary 
staining in Van Gieson's mixture is often an advantage. 

C. Phosphomolybdic-acid Hematoxylin (see page 284). 
— 1. Stain sections twenty minutes to one hour. 

2. Wash out in two or three changes of 50 per cent, 
alcohol until the celloidin becomes completely decolorized 
(about five minutes). 

3. Dehydrate in 95 per cent, alcohol. 

4. Oil, Canada balsam. 

The ganglion-cells are often overstained, especially if the 
tissue has been hardened but recently. The method is 
particularly good for bringing out the axis-cylinders and the 
neuroglia-fibers. 

D. Aniline Blue Stain (see page 286). — The method 
recommended for connective-tissue fibers will also be found 
very useful for the study of the nervous system. The best 
results are obtained after fixation in Zenker's fluid, but fair 



HISTOLOGICAL METHODS. 333 

results can also be obtained after fixation by the method 
advised for neuroglia-fibers — namely, formaldehyde, picric 
acid, and bichromate of ammonium, provided the following 
changes are made in the method : Use a I per cent, solution 
of acid fuchsin ; mordant for several minutes in the phospho- 
molybdic acid ; do not stain more than one to three minutes 
in the aniline blue solution. 

E. Nigrosin. — i. Stain sections in a concentrated aqueous 
solution of nigrosin five to ten minutes. 

2. Decolorize and dehydrate in weak, then in strong, 
alcohol. 

3. Oil, Canada balsam. 

The stain is not very sharp, but is simple and useful, par- 
ticularly for low-power observation. 

Stains for Nissl or Tigroid Bodies. — A. Nissl's 
Stain. — 1. Carefully harden pieces of tissue not over 1 to 
1.2 cm. in diameter in 96 per cent, alcohol. 

2. Cut sections without imbedding, as follows : Remove 
excess of alcohol from tissue with filter-paper; dip base of 
specimen in thick celloidin ; mount on block ; harden in 96 
per cent, alcohol. Moisten knife with 96 per cent, alcohol. 
Sections should always be under T \-§ mm. in thickness. In 
order to be able to compare the number of cells, etc., in one 
case with those in another, the sections should be of uni- 
form thickness. Preserve sections in 96 per cent, alcohol. 

3. Stain the sections in the following solution heated over 
a flame until it bubbles noisily (6o°-70° C.) : 

Methylene-blue, B patent, 1 3.75 ; 

Venetian soap, 1.75 J 

Distilled water, 1 000. 

4. Wash out in — 

Aniline oil, 10 parts ; 

96 per cent, alcohol, 90 " 

until the color is no longer given off in coarse clouds. 

1 Nissl personally prefers and uses the make of Carl Buchner und Sohn, 
Munich. 



334 PATHOLOGICAL TECHNIQUE. 

5. Transfer section to slide ; dry with filter-paper and 
cover with oil of cajuput. 

6. Blot with filter-paper, and then wash with a few drops 
of benzine. 

7. Add a few drops of benzine-colophonium (made by 
dissolving colophonium in benzine for twenty-four hours and 
then decanting). 

8. Hold the slide above the flame until all the benzine is 
driven off. (Nissl no longer recommends burning off the 
benzine.) 

9. Cover-slip. Warm the slide, so that the colophonium 
will spread out evenly between the cover-slip and the slide. 

The specimen is now mounted in a medium in which dif- 
fusion of color cannot take place, so that the stain is practi- 
cally permanent. The best results are obtained with tissues 
which have not been hardened in alcohol over one to four 
days. Contact with water, weak alcohol, and ether must be 
avoided. 

B. Lenhossek's Stain. — The following method will be 
found simpler, but the specimens are not permanent. 

1. Harden sections in 90 per cent, alcohol, then in 96 per 
cent, or in formaldehyde followed by alcohol. Do not keep 
the tissues too long in alcohol. 

2. Imbed sections in celloidin or paraffin, or cut without 
imbedding, as in Nissl's method. 

3. Stain sections in a completely saturated solution of 
thionin for five minutes. 

4. Wash for a few seconds in water. 

5. Differentiate in aniline, 1 part ; 
Absolute alcohol, 9 parts. 

Do not decolorize too long. 

6. Clear in oleum cajuputi. 

7. Xylol. 

8. Canada balsam. 

The granulations can be shown by other stains, such as 
safranin, fuchsin, dahlia, alum-hematoxylin. 

Ganglion-cells ; Dendritic and Axis-cylinder Pro- 
cesses. — Golgi's Methods. — Golgi's methods, although of 



HISTOLOGICAL METHODS. 335 

the greatest value in the study of the normal histology of 
the central nervous system, are of very little use in the study 
of its pathology. The reason of this is the very peculiarity 
that makes the method of value in normal histology — 
namely, that it picks out here and there a cell and stains it 
with all its wealth of processes more or less completely, 
while the neighboring cells are left colorless. If all of the 
cells and their processes were stained, the picture presented 
would be a confused mass. In pathological histology, where 
the presence or absence of certain cells or processes is of 
paramount importance, it is of primary necessity that every 
cell within a given area shall be perfectly stained. 

Golgi introduced three different methods of obtaining the 
stain now called after his name. They are spoken of as the 
slow, the mixed, and the short methods. Golgi himself 
employed principally the first two methods, and they are 
still used for the study of the developed brain and cord. 

The quick method exclusively has been used by Ramon y 
Cajal and other recent investigators for the study of em- 
bryonic nervous tissue. 

The following points are to be borne in mind : The tissue 
should be as fresh as possible, and should be cut into small 
pieces, not over 1 to ij cm. thick — for the quick method 
even thinner. With the corrosive-sublimate method, how- 
ever, larger pieces can be used. 

Large quantities of the solutions should be used — at least 
ten times the volume of the specimen It is best to keep 
the specimens in the solution in the dark, especially in using 
the corrosive-sublimate method. 

Golgi' s Slow Method. — 1. Harden the tissues in a 2 per 
cent, solution of bichromate of potassium two to six weeks. 
In summer fifteen to twenty days are sufficient ; in winter, 
unless the temperature is kept at 25 ° C, one to one and a 
half months will be required. Keep the specimens in the 
dark. Large amounts of the solution should be used, and 
it should be frequently changed, especially during the first 
week. 

2. Transfer either to (a) a f per cent, solution of nitrate 



336 PATHOLOGICAL TECHNIQUE. 

of silver for twenty-four to forty-eight hours ; a longer time 
will do no harm ; or to (b) a J per cent, solution of corrosive 
sublimate — small pieces eight to ten days, large pieces two 
months or more. Change the solution frequently during the 
first few days ; later only when the solution gets yellow. 

This second procedure is recommended for larger pieces 
of tissue than can properly be impregnated by (a). 

Golgi's Mixed Method. — 1. Harden small pieces of tissue 
for three to five days or longer in a 2 per cent, solution of 
bichromate of potassium at 25 ° C, in the dark. 

2. Transfix to a mixture of — 

1 per cent, solution of osmic acid, 2 parts ; 

2 per cent, solution of bichromate of potas- 

sium, 8 " 

for three to eight days. 

3. Place in a f per cent, solution of nitrate of silver for 
twenty-four to forty-eight hours. 

Golgi's Quick Method. — 1. Small pieces of fresh tissue 
are placed directly in the following solution : 

1 per cent, solution of osmic acid, 1 part ; 

3.5 per cent, solution of bichromate of potassium, 4 parts, 
for several days (three to eight). 

2. They are then transferred to a large amount of a f per 
cent, solution of nitrate of silver for one, two, or six days. 

The length of time the tissues should remain in the 
osmic-acid and bichromate-of-potassium solution depends on 
what elements it is desired to impregnate. In the human 
cord the time is in general the following : 

1. Neuroglia, 2-3 days ■ 

2. Nerve-cells, 3-5 " 

3. Nerve-fibers and collaterals, 5-7 " 

The further treatment of the tissues impregnated by these 
methods is as follows : Alcohol must be avoided as much as 
possible. The tissues are usually firm enough to cut after 
the impregnation ; if not, place in absolute alcohol for fifteen 
to thirty minutes. The sections should be rather thick, ^ 



HISTOLOGICAL METHODS. 337 

to -^q mm. They may be made free hand with a razor or in 
the microtome. For either method the tissues can be held 
between pieces of elder-pith, or may be quickly imbedded in 
celloidin by dehydrating for a few minutes in absolute alco- 
hol and then placing in a thick solution for five minutes. 
From the celloidin they are mounted in elder-pith or on 
blocks, and placed for a short time in 80 per cent, alcohol to 
harden. 

Treatment of Sections. — 1. Dehydrate quickly in alcohol. 

2. Clear in oil of cloves or bergamot. 

3. Wash off with xylol. 

4. Mount without a cover-glass in xylol damar, and dry 
quickly at 40 C. 

The mounted sections must be protected from the light 
and from dust as much as possible. Cajal has modified 
Golgi's quick method by repeating the steps (Cajal's so- 
called double method) so as to get a more perfect impregna- 
tion. The same osmic-acid and bichromate-of-potassium 
solution may be used over again, or a fresh solution, con- 
taining about one-half as much osmic acid, is made up fresh. 
The silver solution should be taken fresh each time. Len- 
hossek, Weigert, and others have obtained very good Golgi 
preparations with tissues first fixed in formaldehyde. 

Of the various methods proposed for fixing the Golgi 
stains so that contrast-stains could be used with them and 
the specimens protected by cover-slips, the simplest and 
most practical seems to be that advocated by Kallius. 

The Method of Kallius for Fixing Golgi Stains.— The 
method depends on the employment of a photographic 
developer to reduce the bichromate of silver to metallic 
silver. 

1. Place sections for several minutes in a solution com- 
posed of 1 part of the following developer : 



Hydrochinon, 


1 ; 


Sulphite of sodium, 


3; 


Carbonate of potassium, 


15; 


Water, 


5/5. 


22 





33 8 PATHOLOGICAL TECHNIQUE. 

plus one-third to one-half as much absolute alcohol until 
the sections become gray to black in color. If too much 
alcohol is added, the carbonate of potassium will be pre- 
cipitated, but will redissolve on the addition of a little more 
developer. 

2. jo per cent, alcohol for ten to fifteen minutes. 

3. Hyposulphite of sodium (20 per cent, aqueous solu- 
tion). 

4. Wash thoroughly in a large amount of water for twenty- 
four hours. 

5. Alcohol, oil, Canada balsam ; cover-glass. 

Cox's Modification of Golgi's Corrosive-sublimate 
Method. — The same black pictures are obtained by this 
method as by Golgi's, but with this difference, that nearly all 
of the cells in the section are impregnated. This is an ad- 
vantage when the topographical arrangement of the cell- 
layers is desired, but a disadvantage when it comes to the 
study of individual cells, because on account of the luxuri- 
ance of the impregnation such a study is rendered impos- 
sible. Small pieces of nervous tissue are placed in the fol- 
lowing solution : 

Bichromate-of-potassium 5 per cent, solution, 20 ; 

Corrosive-sublimate 5 per cent, solution, 20 ; 

Distilled water, 30-40 ; 

Simple chromate-of-potassium 5 per cent, solution, 16. 

The time required for impregnation is a month in summer 
and two to three months in winter. The after-treatment is 
the same as for Golgi preparations. 

Axis- cylinders and their Terminal Processes. — 
The three methods most in use for the study of central and 
peripheral nerve-fibers and their terminations are the gold, 
the Golgi, and the methylene-blue methods. All three may 
give beautiful results, but, as a rule, they are very unreliable. 
Their use is confined almost wholly to the study of normal 
tissues. 

Gold Stain for Nerve-fibers. — For the application of the 
gold method to fresh tissues see p. 302. 



HISTOLOGICAL METHODS. 339 

Various attempts have been made to devise a reliable 
method of employing chlorid of gold for staining nerve- 
fibers in sections of hardened tissues. The results have not 
been altogether successful. The best results can probably 
be obtained by — 

A. Gerlacks Method. — 1. Harden tissues in a 1-2 per cent, 
solution of bichromate of ammonium for one to three weeks ; 
cut sections without passing through alcohol, which must be 
avoided. 

2. Place the sections in a very dilute solution (y^ pet- 
cent.) of the double chlorid of gold and potassium very 
slightly acidulated with hydrochloric acid, for ten to twelve 
hours, until they become slightly violet in color. 

3. Wash in a solution of hydrochloric acid 1, to water 
2000-3000. 

4. Place for ten minutes in a ^ per cent, solution of hy- 
drochloric acid in 60 per cent, alcohol. 

5. Absolute alcohol, oil of cloves, Canada balsam. 
Another method frequently recommended is the following : 

B. Freud's Gold Stain for Nerve -fibers. — 1. Harden tissues 
in Erlicki's or Muller's fluid, followed by alcohol. Imbed in 
celloidin. 

2. Stain sections three to five hours in 1 per cent, solution 
of chlorid of gold, and 95 per cent, alcohol, equal parts. 

3. Wash in water. 

4. Reduce in — 

Caustic soda, I ; 

Distilled water, 6, 

for two to three minutes. 

5. Wash in water. 

6. Place for five to fifteen minutes in a 10 per cent, solu- 
tion of iodid of potassium. 

7. Wash in water. 

8. Alcohol, oil, Canada balsam. 

C. Stroebe's Aniline-blue Stain for Nerve-fibers in Hard- 
ened Sections. — Harden tissues in Muller's fluid. 1. Stain 



34° PA THOL O GICAL TECHNIQ UE. 

one-half to one hour in a saturated aqueous solution of ani- 
line-blue. 

2. Wash in water. 

3. Transfer to a small dish of alcohol to which are added 
20 to 30 drops of a I per cent, alcoholic solution of caustic 
potash (caustic potash 1 to alcohol 100: let the mixture 
stand for twenty-four hours ; then filter). In one to several 
minutes the sections become bright brownish-red and trans- 
parent. 

4. Transfer to distilled water for five minutes. The sec- 
tion becomes bright blue again. 

5. Stain in a half-saturated aqueous solution of safranin 
one-quarter to one-half hour long. 

6. Wash out and dehydrate in absolute alcohol. 

7. Xylol, Canada balsam. 

D. Clilorid-of-iron and dinitroresorci?i method for the study 
of degenerated peripheral nerves : 

1 . Place fresh pieces of peripheral nerves for several days 
in a solution of — 

Chlorid of iron, 1 part ; 

Distilled water, 4 parts. 

2. Wash out thoroughly in water. 

3. Transfer to a saturated solution of dinitroresorcin in 75 
per cent, alcohol for several weeks. 

4. Wash, dehydrate, imbed, etc. 

A permanent green color is formed which stains the nerves 
green and brings out the green axis-cylinders very sharply. 

The stain will succeed with preparations which have been 
hardened in Flemming's solution or Muller's fluid. 

Golgi's methods are sometimes employed for the study of 
the terminal processes of nerve-fibers (for directions see 

P- 334). 

Methylene-blue Stain for Nerve-fibers. — The methylene- 
blue method is due to Ehrlich. Many modifications of the 
original procedure have been suggested with a view to mak- 
ing the results surer or the specimens more permanent. 
Tissues can be stained either by injection or by immersion. 



HISTOLOGICAL METHODS. 34 1 

The methylene-blue used should be Grubler's " rectified 
methylene-blue. for vital injection." 

For injection in the blood- or lymph-vessels of live or 
dead animals a 1 to 4 per cent, solution in normal salt solu- 
tion is recommended. The injected organs are exposed to 
the air until a bluish tint is visible. As soon as the greatest 
intensity of stain is reached (five minutes to two hours) the 
color in the preparation is fixed by placing small bits of the 
tissue in a freshly-filtered, cold, saturated, aqueous solution 
of picrate of ammonium, or, better still, in the solution given 
below, recommended by Bethe. 

Very small or thin pieces of tissue intended for staining by 
immersion (the method employed for human tissues) are 
placed in a very dilute solution vrV" T5 P er cent of methyl- 
ene-blue in normal salt solution. Lavdowski recommends 
very highly a solution of methylene-blue in egg-albumin, 
either alone or combined with chlorid of sodium or ammo- 
nium. The white of egg is freed from the thicker portions or 
filtered. When the experiment is to last some time, add to 
the egg-albumin an equal part of a J per cent, solution of 
chlorid of sodium or of a \ per cent, solution of chlorid of 
ammonium. The tissue, protected by a large dish, is exposed 
to the air for fifteen minutes to twelve hours, until the maxi- 
mum stain is obtained. 

The stain may then be fixed by the method already given, 
or, better still, in the following manner : 

Bethe 's Method of Fixing Methylene-blue Stains of Nerve- 
fibers. — 1. Wash off excess of color with normal salt solu- 
tion. 

2. Place in — 

Molybdate of ammonium, I gr. ; 

Distilled water, 10 c.c. ; 
Peroxid of hydrogen, I " 

Hydrochloric acid, 1 drop. 

A precipitate forms on making up the solution, but disap- 
pears on shaking. The solution will keep eight days, but is 
best made up fresh each time. It should be used as cold as 



34 2 PATHOLOGICAL TECHNIQUE. 

possible, preferably surrounded by a mixture of ice and salt. 
Leave the tissue in the cold solution for from two to five 
hours, and then for a while longer at the room-temperature. 

3. Wash one half to two hours in running water. 

4. Dehydrate and harden as quickly as possible (not over 
twelve to twenty-four hours) in cold absolute alcohol. (The 
color is soluble in warm alcohol.) 

5. Clear in xylol. 

6. Imbed in paraffin. 

The sections may be mounted directly or brought into 
water and stained with alum-cochineal for contrast. If a little 
osmic acid be added to the fixing solution after the speci- 
mens have been in it for a while, a more permanent methyl- 
ene-blue stain is obtained. 

Stains for the Myelin-sheath. — The myelin-sheath 
of nerve-fibers is a form of fat, and like it possesses the 
property of reducing osmic acid, by means of which a selec- 
tive sheath stain can be obtained. Unfortunately, however, 
the osmic acid penetrates to but a very slight depth. Three 
methods employing osmic acid are given, but they are all 
expensive and not so satisfactory as those employing hema- 
toxylin. 

The differential hematoxylin stain, originated by Weigert, 
and ordinarily used, depends on some chemical reaction 
which takes place between the myelin and a chrome salt, in 
consequence of which the myelin is fixed so that it will not 
later be dissolved out by alcohol or ether, and at the same 
time is so mordanted that it can be deeply stained with 
hematoxylin, to which it clings when treated with certain 
decolorizers. This reaction between the myelin and the 
chrome salts in general use takes place very slowly at the 
ordinary temperature ; six weeks to several months are 
usually required. Weigert's latest method depends on the 
interaction of two chrome salts in the same solution, in 
consequence of which the time needed for this reaction or 
mordanting is reduced to four days. The solution may be 
used alone, but is best combined with formaldehyde or used 
after it. 



HISTOLOGICAL METHODS. 343 

A. Weigert's Myelin-sheath Stain. — In this method five 
steps are involved, but the first two can be, and often are, 
combined in one. % These five steps are fixation, primary 
mordanting, secondary mordanting, staining, and differentia- 
tion. These different steps will be considered separately. 

1. Fixation. — Place the tissues in a 4 per cent, solution of 
formaldehyde (10 per cent, solution of formalin) for four 
days to several weeks or indefinitely, using several times the 
volume of the tissue. Change the solution at the end of 
twenty-four hours, and thereafter whenever it becomes cloudy. 
Large masses oi nervous tissue, like the medulla and pons 
or the basal ganglia, should be fixed in formaldehyde for 
one to three weeks. 

2. Primary Mordanting. — Cut the tissues fixed in formal- 
dehyde into slices not over 1 cm. thick, and place in the 
following solution for four to five days at room-temperature : 

Bichromate of potassium, 5 ; 

Fluorchrom, 2 ; 

Water, ad 100. 

Steps 1 and 2 may be combined by adding 4 per cent, of 
formaldehyde to the mordanting solution and placing the 
fresh tissues directly in the mixture. 

3. Secondary Mordanting. — Transfer the tissues to the 
following solution for twenty-four to forty -eight hours : 

Acetate of copper, 5.0; 

Acetic acid, 36 per cent, solution, 5.0; 

Fluorchrom, 2.5 ; 

Water, ad 100.0 

(For method of preparation see page 284.) 

Weigert always transfers blocks of tissue to the secondary 
mordant, of which the function is to intensify the staining 
reaction. Many workers, however, prefer to employ the 
secondary mordant on sections only. In this case they 
place the tissues directly from the first mordant into graded 
alcohols, imbed in celloidin, and cut sections before step 3. 
Either way gives good results, but the first is the simpler. 



344 PATHOLOGICAL TECHNIQUE. 

Weigert also recommends the following iron solution as a 
secondary mordant, but if applied to blocks of tissue, they 
must be well washed in running water before being dehy- 
drated and imbedded in celloidin, because otherwise the 
iron will rust the knife badly. Of course, if this mordant is 
applied to sections only, prolonged washing is not necessary : 

Iron alum (ammonioferric alum), 5 ; 

Acetic acid, 5 ; 

Water, ad 100. 

After the secondary mordant the tissue is dehydrated in 
graded alcohols, imbedded in celloidin, and sections cut in 
the usual manner. 

4. Staining. — Stain sections in the following solution for 
twelve to twenty-four hours : 

Ripened 10 per cent, solution of hematoxylin in 
absolute alcohol, 10; 

Saturated aqueous solution of carbonate of 

lithium, 1 ; 

Water, 90. 

Keep on hand as a stock solution a 10 per cent, solution 
of hematoxylin in absolute alcohol. At least ten days of 
exposure to light are required to ripen this solution so that 
it can be used for staining. Combine with the carbonate of 
lithium and the water at the time of using in such propor- 
tions as are wanted for immediate use. Wash the sections 
thoroughly in water before differentiation. 

Another staining solution w T hich Weigert recommends 
highly is the following — it consists of two parts : 

(a) Liquor ferri sesquichlorati (officinal), 4 c.c. ; 
Water, 96 " 

(b) Ripened 10 per cent, solution of hema- 

toxylin in absolute alcohol, 10 " 

96 per cent, alcohol, 90 " 

Mix thoroughly equal parts of these two solutions just 
before using, and pour over the sections. Stain overnight 



HISTOLOGICAL METHODS. 345 

or longer at room-temperature. Pour off solution and wash 
with water. 

5. Differentiation. — The sections are differentiated in the 
following solution which it is sometimes advisable to dilute 
with water : 

Borax, 2.0 ; 

Ferricyanid of potassium, 2.5 ; 

Water, IOO.O. 

After the first staining method given above the decolor- 
ized tissues appear yellow ; after the iron-hematoxylin solu- 
tion they are colorless. Moreover, this latter method stains 
the very finest fibers and at the same time the coarse fibers, 
such as occur, for example, in the nerve-roots. 

After differentiation the sections should be thoroughly 
washed in water, dehydrated in alcohol, cleared in the anilin 
oil-xylol or carbol-xylol mixture, and mounted in xylol 
balsam. 

The steps of the process may be summed up as follows : 

1. Fix in 10 per cent, formaldehyde four days or longer. 

2. Mordant in the bichromate of potassium-fluorchrom 
solution four to five days. 

3. Mordant in the acetate of copper-fluorchrom solution 
twenty-four to forty-eight hours, or in the iron solution 
twenty-four to forty-eight hours. 

4. Dehydrate in graded alcohols. 

5. Imbed in celloidin. 

6. Stain sections in the alcoholic hematoxylin solution or 
in the iron-hematoxylin solution for twelve to twenty-four 
hours. 

7. Wash off in water. 

8. Differentiate in the borax-ferricyanid of potassium 
solution. 

9. Wash thoroughly in water. 

10. Dehydrate in alcohol. 

11. Clear in the anilin oil-xylol or carbol-xylol mixture. 

12. Mount in xylol balsam. 

B. Pal's Modification of Weigert's Myelin -sheath Stain. 



346 PATHOLOGICAL TECHNIQUE. 

— I. Fixation and primary mordanting as for Weigert's 
method. 

2. Place sections for several hours in a y 2 per cent, aqueous 
solution of chromic acid, or for a longer time in a 2-3 per 
cent, solution of bichromate of potassium. This step is 
often omitted, especially when the tissues have been but 
recently mordanted. 

3. Transfer sections to Weigert's alcoholic hematoxylin 
solution for twenty -four to forty-eight hours (if necessary 
for an hour in the incubator at 37 C). This solution is as 
follows : 

Ripened 10 per cent, solution of hematoxylin 

in absolute alcohol, 10. 

Water, 90. 

4. Wash in water plus 1 to 3 per cent, of a saturated 
aqueous solution of carbonate of lithium until the sections 
appear of a uniform deep-blue color. 

5. Differentiate for twenty seconds to five minutes in a J 
per cent, aqueous solution of permanganate of potassium 
until the gray matter looks brownish-yellow. 

6. Transfer to the following solution : 

Oxalic acid, I ; 

Sulphite of potassium, I ; 

Water, 200. 

for a few seconds until the gray matter is colorless or 
nearly so. 

7. Wash thoroughly in water. 

8. Dehydrate in 95 per cent, alcohol. 

9. Oil, Canada balsam. 

Steps 5 and 6 sometimes have to be repeated when the 
differentiation has not been complete. 

Of all the numerous modifications of Weigert's original 
myelin-sheath stain, the only one that has found general 
acceptance is Pal's. It has the following advantages : It 
gives very clear pictures ; everything except the sheaths is 
completely decolorized, so that contrast-stains are possible ; 



HISTOLOGICAL METHODS. 347 

it is more successful with thick sections than Weigert's 
method ; the separate steps are quicker. On the other 
hand, the danger of decolorizing the sheaths of the finer 
fibers is greater. 

C. Bxner's Stain. — The tissue should be obtained as 
soon as possible after death, although the method will 
succeed with tissues even over twelve hours old. 

i. Place pieces of brain or cord not over ^ cm. thick in a 
I per cent, aqueous solution of osmic acid, using at least 
ten times as much fluid as the volume of the specimen. 

2. Change the osmic-acid solution on the second day. 

3. After five or six days wash thoroughly in water. 

4. Dehydrate, imbed, etc. 

5. Examine sections in glycerin rendered slightly ammo- 
niacal. 

The myelin-sheaths appear gray to black. The prepara- 
tions are not permanent. 

This procedure has been almost entirely replaced by Wei- 
gert's method, which has numerous advantages. Lately, 
however, it has been brought forward again by Heller, who 
uses a photographic developer to reduce the osmic acid and 
to make possible permanent mounts. He has lately pub- 
lished the following method for sections, but it cannot be 
unconditionally recommended : 

D. Heller's Myelin-sheath Stain. — 1. Harden as for the 
Weigert method (Heller used Miiller's fluid). 

2. Imbed in celloidin. 

3. Place sections in a 1 per cent aqueous solution of os- 
mic acid for ten minutes in thermostat or for half an hour 
at room-temperature. 

4. Wash in water. 

5. Reduce in the following developer: 

Sulphate of sodium, 125 ; 

Carbonate of sodium, 70; 

Water, 500 ; 

Pyrogallic acid, 15. 



348 PATHOLOGICAL TECHNIQUE. 

6. Wash in water. 

7. Differentiate in an aqueous solution of permanganate 
of potassium, ^ per cent, or less. 

8. Remove the brown of the permanganate of potassium 
in a 1 per cent, aqueous solution of oxalic acid. 

9. Wash in water. 

10. Alcohol, oil, Canada balsam. 

E. Robertson's Modification of Heller's Myelin-sheath 
Stain. — 1. Harden in Weigert's fluorchrom-copper solution 
plus 4 per cent, of formaldehyde ; in other words, use the 
mordant for neuroglia-fibers (page 350) eight to ten days. 

2. Wash off in water. 

3. Alcohol ; imbed in celloidin. 

4. Stain sections in a 1 per cent, solution of osmic acid 
half an hour in the dark. 

5. Place in a 5 per cent, aqueous solution of pyrogallic 
acid for half an hour. 

6. Differentiate in a \ per cent, aqueous solution of per- 
manganate of potassium one to four minutes. 

7. Remove brown color in 1 per cent, oxalic acid three to 
five minutes. 

8. Alcohol, oil, balsam. 

It is important to wash carefully in water between each 
of the staining steps. 

Stains for Neuroglia-fibers. — It is possible to obtain 
a differential stain of the neuroglia-fibers in man by several 
different methods. The tissue must be as fresh as pos- 
sible. The best results are obtained with tissues placed 
in the fixing solution within one hour after death. After 
four to six hours the results are only fair ; after twenty-four 
hours they are practically nil. The chemical property in 
the neuroglia-fibers on which the differential stain depends 
has undergone some chemical change or has disappeared. 
It is retained longest where the fibers are most numerous, 
as about the central canal. 

For most of the methods formaldehyde must be used as 
the fixative, either alone or combined with certain other 
reagents mentioned below, but one method depends on fixa- 



HISTOLOGICAL METHODS. 349 

tion in alcohol. According to Weigert, who first fully 
recognized the value of formaldehyde in preserving neu- 
roglia-fibers, the best strength to use is a 4 per cent, solu- 
tion (2. e., a 10 per cent, solution of formaline, etc.). The 
pieces of tissue in which it is desired to stain the neuroglia- 
fibers must be cut very thin — never over -^ cm. thick, and 
preferably thinner. With thicker pieces only the surface 
sections are of any value. 

The tissues after fixation must be mordanted, so as to 
render the staining more intense ; without mordanting only 
a few of the fibers will stain. 

The methods of staining neuroglia-fibers are given in the 
order of their publication. The second method (Weigert's) 
gives a more intense stain than the first, but has the draw- 
back of staining degenerated nerve-fibers. The third method 
is particularly useful for class purposes, because a large 
number of sections can be stained all at one time. 

A. Mallory's Differential Stain for Neuroglia-fibers. — 
1. Fix in a 4 per cent, aqueous solution of formaldehyde 
four days or more. 

2. Place in a saturated aqueous solution of picric acid 
four to eight days. 

Steps 1 and 2 may be combined by adding 10 parts of 
the 40 per cent, formaldehyde solution to 90 parts of the 
saturated aqueous solution of picric acid. 

3. Transfer to a 5 per cent, aqueous solution of bichro- 
mate of ammonium for four to six days in the incubator at 
37 C, or for three to four weeks at room-temperature. 
Change the solution on the second day. 

4. Place directly in alcohol. 

5. Imbed in celloidin. 

6. Fasten sections to slide by means of ether-vapor. 

7. Stain in aniline-gentian-violet fifteen to twenty minutes. 

8. Wash off with normal salt solution. 

9. Iodin solution, 1:2: 100, for one minute, or a stronger 
solution for a few seconds. 

10. Wash off with water. 

11. Dry with filter-paper. 



350 PATHOLOGICAL TECHNIQUE. 

12. Decolorize in equal parts of aniline and xylol. 

13. Wash off thoroughly with xylol. 

14. Xylol balsam. 

The neuroglia-fibers, fibrin, nuclei, and to some extent 
the red blood-globules, are stained blue. The other tissue- 
elements are colorless. By very faintly tinting the aniline- 
and-xylol mixture with fuchsin, which is readily soluble in 
aniline, the other tissue-elements are easily brought out, but 
the finer neuroglia-fibers are likely to lose their blue color. 

Weigert's Differential Stain for Neuroglia-fibers. — A. 
Fix thin pieces of tissue, not over -J cm. thick, in a 4 per 
cent, solution of formaldehyde for at least four days. 

B. Mordant in the following solution for four to five days 
in the incubator or for eight days at room-temperature : 

Acetate of copper, 5 gr. ; 

Acetic acid, 36 per cent, solution, 5 c.o. ; 

Fluorchrom, 2.5 gr.; 

Water, ad 100 c.c. 

Boil the fluorchrom and water in a covered dish, turn off the 
gas, add the acetic acid and then the acetate of copper ; stir 
briskly until the latter is dissolved, then cool. The solution 
remains clear. 

(Steps I and 2 may be combined by adding 4 per cent, of 
formaldehyde to the above solution ; change on the second 
day ; harden eight days.) 

C. Wash off in water ; dehydrate in alcohol ; imbed in 
celloidin. 

D. Reduction of copper salt in sections : 

1. Place the sections, which must not be over .02 mm. 
thick, in a ^ per cent, aqueous solution of permanganate of 
potassium for ten minutes. 

2. Wash off with water. 

3. Decolorize and reduce for two to four hours in the fol- 
lowing solution, carefully filtered : 

Chromogen, 5 gr. ; 

Formic acid (sp. gr. 1. 20), 5 c.c. ; 

Water, ad 100 " 



HISTOLOGICAL METHODS. 35 I 

to 90 c.c. of which are added just before using 10 c.c. of a 
10 per cent, solution of sulphite of sodium. 

The sections lose their color in a few minutes, but are best 
kept in the solution as long as above directed. 

The sections can now be stained in the manner to be de- 
scribed, but the color of the fibers will be more intense if the 
following steps are added, and a slight yellowish contrast- 
stain is obtained for the ganglion and ependymal cells and 
for the larger nerve-fibers. This step has one disadvantage, 
however : the connective-tissue fibers stain blue after it. 

E. Further reduction of copper salt : 

1. Wash twice in water. 

2. Place sections in a carefully filtered saturated (5 per 
cent.) aqueous solution of chromogen overnight. 

3. Wash in water. 

4. The sections are now ready for staining or may be pre- 
served until wanted in — 

80 per cent, alcohol, 90 c.c. 

5 per cent, oxalic acid, 10 " 

F. Staining of neuroglia-fibers : 

1. Lift section from large dish of water on slide freshly 
cleaned with alcohol ; blot with filter-paper (method recom- 
mended by Weigert for attaching sections to slide). 

2. Stain in the following mixture : 

Saturated solution of methyl-violet in 

70-80 per cent, alcohol, 100 c.c. ; 

(saturated with aid of heat ; decanted 
when cold). 

5 per cent, aqueous solution of oxalic 

acid, 5 " 

The oxalic acid is added to render the preparations more 
lasting. The staining is practically instantaneous. 

3. Wash off with normal salt solution. 

4. Iodin solution : 5 per cent, iodid-of-potassium solution 
saturated with iodin. It is simply poured on and then off, 
as the reaction is instantaneous. 



352 PATHOLOGICAL TECHNIQUE. 

5. Wash off with water and blot with filter-paper. 

6. Decolorize thoroughly in equal parts of xylol and 
aniline oil. 

7. Wash repeatedly with xylol or the stain will not keep. 

8. Canada balsam. 

The sections keep better if exposed for from two to five 
days to diffuse light before being put away. 

C. Differential Stain of Neuroglia-fibers by Means of 
Phosphotung , stic-acid Hematoxylin (Mallory). — 1. Fix and 
mordant tissues in exactly the same way as in the first 
method given for neuroglia-fibers — viz. : 

(a) Fix in 4 per cent, aqueous solution of formaldehyde 

four days. 

(b) Saturated aqueous solution of picric acid four days. 

(c) 5 per cent, aqueous solution of bichromate of am- 

monium four to six days in incubator or three 
to four weeks at room-temperature. 

(d) Alcohol, celloidin, etc. 

2. Place the sections in a } per cent, aqueous solution of 
permanganate of potassium for fifteen to thirty minutes. 

3. Wash in water. 

4. Five per cent, aqueous solution of oxalic acid one to 
two hours. 

5. Wash in two or three changes of water. 

6. Stain in phosphotungstic-acid hematoxylin for twenty- 
four hours to two or three days. 

7. Wash quickly in water. 

8. Place in a strong (20 to 30 per cent.) alcoholic solution 
of ferric chlorid for five to twenty minutes, rarely longer. 
It is best to make up the solution as needed, as it does not 
keep well : the exact strength used is not important. 

9. Wash thoroughly in water. 

10. Alcohol, oleum origani cretici, xylol balsam. 

The nuclei, neuroglia-fibers, and fibrin stand out sharply 
of a clear blue color; everything else is decolorized or 
appears of a pale yellowish or grayish tint. The results 
obtained are practically identical with those obtained by 
either of the modified fibrin stains, and the method has the 



HISTOLOGICAL METHODS. 353 

decided advantage of being applicable to any number of 
sections at once. 

Benda's Stain for Neuroglia Fibrils. — Hardening. — I. 
Fix fresh material for at least two days in 90 to 93 per cent, 
alcohol. 

2. Place thin sections (not over 5 mm. thick) in 10 per 
cent, nitric acid for twenty-four hours. 

3. Two per cent, aqueous solution of bichromate of potas- 
sium, twenty-four hours. 

4. One per cent, aqueous solution of chromic acid, forty- 
eight hours. 

5. Wash in running water for twenty-four hours, harden in 
graded alcohols, imbed in paraffin. 

Staining. — Iron-alizarin-toluidin-blue Stain. — 1 . Mordant 
the sections for twenty-four hours in a 4 per cent, solution 
of iron-alum. 

2. Wash off in running water. 

3. Twenty-four hours in dilute amber-yellow aqueous 
solution of sodium sulphalizarate. 

4. Dip in water and blot with filter-paper. 

5. Stain in a I per cent, aqueous solution of toluidin-blue, 
warm until steam rises, then let it stain about fifteen minutes 
in the cooling fluid ; or stain one to twenty-four hours in 
cold toluidin-blue. 

6. Dip in 10 per cent, acetic acid or in very dilute picric 
acid. 

7. Dry with filter-paper and dip in absolute alcohol. 

8. Differentiate in beech creasote about 10 minutes, con- 
trolling result with microscope. 

9. Dry with filter-paper; xylol balsam. 
Degenerations of the Nervous System. — The same 

methods apply to the study of degenerations in nervous tis- 
sue that apply elsewhere, except in the demonstration of 
fat. Both myelin and fat reduce osmic acid, so that the 
ordinary test for fat in the hardened tissues fails. Marchi 
and Algeri, however, have shown that after myelin has been 
mordanted for eight days or over in M tiller's fluid or other 
solution of the bichromates, it loses the property of reduc- 

23 



354 PATHOLOGICAL TECHNIQUE. 

ing the osmic acid, while fat retains the property unimpaired. 
On this peculiarity is based their method for differentiating 
fat from myelin. 

Marchi and Algeri's Method for Staining" Fatty De- 
generated Myelin-sheaths of Nerve-fibers. — I. Harden in 
Muller's fluid or in formaldehyde, followed by Miiller's fluid, 
for eight days to three months. 

2. Transfer tissue for five to eight days directly into the 
following solution : 

Muller's fluid, 2 parts ; 

I per cent, osmic-acid solution, I part. 

3. Wash out thoroughly in water. 

4. Dehydrate in alcohol. 

5. Imbed in celloidin. 

6. Clear in chloroform and mount in properly prepared 
chloroform balsam (see page 300). 



EXAMINATION OF THE BLOOD. 

The specific gravity of the blood varies but slightly and 
averages 1055. For clinical purposes the method of Ham- 
merschlag is the best for estimating the specific gravity. The 
method depends upon the physical law that a body which re- 
mains suspended in a fluid must have the same specific grav- 
ity as that fluid. The fluid selected is a mixture of chloro- 
form (specific gravity 1526) and benzol (specific gravity 0.889). 
A drop of blood does not mix with either fluid. 

A small test-tube holding about 10 c.c. is half filled with 
a mixture of benzol and chloroform. This mixture should 
have the specific gravity of from 1050 to 1060. A drop of 
freshly-drawn blood is allowed to fall into this mixture, care 
being exercised that the drop falls directly into the fluid. 
Chloroform or benzol is added according as the drop of blood 
sinks to the bottom or floats on the surface of the fluid. It 
is necessary in adding either of the fluids to thoroughly mix 
them by gentle rotating movements without breaking the 



HISTOLOGICAL METHODS. 355 

blood-drop. If the drop floats on the surface, it is better to 
add sufficient benzol to make it sink to the bottom, and then 
add chloroform until it becomes suspended in the fluid. 
Too large a drop of blood is liable to be broken up in mix- 
ing the fluids, and this must be avoided. When the drop re- 
mains suspended in the thoroughly mixed fluids the latter is 
filtered and the specific gravity tested. 

Apparatus Used in the Examination of the Blood. 
— An accurate examination of the blood can be made only 
by the strictest observance of cleanliness and attention to de- 
tails. It has been deemed wise, therefore, to devote the 
greater part of this article to a description of the various 
steps of the process for the benefit of those who are unfa- 
miliar with the technique. 

With this object in view it is not necessary to describe the 
numerous instruments which have been devised for examin- 
ing blood or to refer to many of the staining fluids. The 
Thoma-Zeiss hemocytometer, or blood-counting instrument 
(Fig. 117), is the one which is generally employed to count 
the red and white blood-corpuscles, and consists of a glass 
slide on which the blood-corpuscles are counted and a pi- 
pette for mixing the blood and diluting fluid. The counting 
slide has a thin square plate of glass cemented on its surface : 
a circular opening in the center of this plate is nearly filled 
by a glass disc -^ mm. thinner than the square plate which 
surrounds it. A series of horizontal and vertical lines on the 
surface of the disc divides it into squares, the sides of which 
are -^ mm. long. Additional lines placed close together 
divide this surface into quadrants. Each quadrant contains 
sixteen of the small squares. 

The pipette consists of a capillary tube which expands 
into an ovoid chamber above. The chamber contains a glass 
pearl, which assists in mixing the blood and diluting fluid. 
The capillary tube has a capacity of 1 mm. and is graduated 
to tenths. Above the ovoid chamber is a line marked 10 1 mm. 
A dilution of I to 100 or 1 to 200 is obtained by sucking 
the blood up to the mark 1. or 0.5, and the diluting fluid up 
to the mark 10 1. 



35^ 



PA THOL GICAL TECHNIQ UE. 




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FIG. 117. — Thoma-Zeiss blood-counting apparatus (Limbeck) : A.melangeur; 
a, capillary tube in which the blood is taken ; b, chamber for mixing the blood 
with the diluting solution ; c, glass ball to aid in mixing the blood with the dilut- 
ing solution ; B, cross-section of the chamber in which the blood is counted ; 

C, section of the field on which the blood is counted, showing thirty-six squares ; 

D, diagram of the whole field. 



HIS TO I O GICAL ME THODS. 



357 



A second pipette for counting the white corpuscles is grad- 
uated in such a way as to give a dilution of I to I O or I to 20. 

For clinical purposes the Von Fleischl hemometer (Fig. 1 1 8) 
is generally used to estimate the hemoglobin. This instru- 
ment is fairly accurate, but for percentages of hemoglobin 




Fig. 118. — Von Fleischl's hemometer : a, stand ; b, narrow wedge-shaped piece 
of colored glass fitted into a frame (c) which passes under the chamber; d, hol- 
low metal cylinder, divided into two compartments, which holds the blood and 
water; e, white plate from which the light is reflected through the chamber; 
/, screw by which the frame containing the colored glass is moved ; g, capillary 
tube to collect the blood ; h, pipette for adding the water ; i, opening through 
which may be seen the scale indicating percentage of hemoglobin. 



below 50 per cent, it is safe to allow 5 per cent, for error in 
the apparatus. The instrument consists of a metal stand (a) t 
a narrow wedge-shaped piece of colored glass (d), a hollow 
metal cylinder (d), and capillary tubes [g). The metal stand 
(a) is fitted with a flat stage above, in which is an aperture 
for holding the cylinder (d). On the under surface of this 



358 PATHOLOGICAL TECHNIQUE. 

stage are two metal rims in which the glass wedge (b) fits. 
These rims are arranged so as to allow the glass wedge 
to move across the aperture by means of an adjustment 
screw. The glass wedge (b) is colored red, the degree of 
color becoming more intense toward the thick end. The 
glass is held in a metal frame, on one of whose sides 
parallel with the glass there is a scale of percentages from 
o. to 120, corresponding to the intensity of the color in the 
glass. The metal cylinder (d) is divided into two equal com- 
partments by a thin metal partition which extends from one 
end of the cylinder to the other. One end of the cylinder 
is closed by a piece of glass. The blood is collected in the 
capillary tube (g). 

Preparation of Apparatus. — Three things are essential 
in order to make a satisfactory examination of the blood : 
the apparatus must be absolutely clean ; the various stages 
in the process must be performed rapidly, because a very 
slight coagulation of the blood will interfere with any of the 
tests ; and the work must be done accurately. 

Many of the details which follow may appear trivial to 
one who is unfamiliar with the methods employed in making 
blood-examinations. Experience will convince such an one 
to the contrary. All apparatus should be thoroughly 
cleaned and dried immediately after completing a blood-ex- 
amination. The " mixing pipette " for estimating the blood- 
corpuscles can be readily cleaned by removing the rubber 
tubing and fixing it to the other end of the pipette, or a 
double atomizer bulb, such as is used on the Paquelin cau- 
tery, may be substituted. The pipette should be cleaned 
with water, alcohol, and finally with ether, until it is dry in- 
side. If the alcohol fails to remove all of the staining fluid 
from the inside of the pipette and from the glass pearl, acid 
alcohol (hydrochloric acid I part, alcohol (70 per cent.) 100 
parts) may be used. This should be followed by alcohol, 
and then by ether. The blood-counting slide may be cleaned 
with water. If any of the staining fluid adheres to the slide, 
it may be removed with alcohol. If alcohol is used to clean 
the counting slide, it must be used rapidly and the slide 



HISTOLOGICAL METHODS. 359 

washed with water, because alcohol dissolves the cement by 
means of which the thin square of glass and the disc are 
fastened to the slide. The capillary tubes used for estimat- 
ing the hemoglobin should be cleaned in the same way as 
the " mixing pipette." It has been found that the blood fills 
the capillary tube more readily if the latter is cleansed a 
second time with water directly before making the blood- 
examination. If this is done, it is necessary to thoroughly 
dry the tube afterward. This may be accomplished by re- 
moving most of the water and drying the remaining moist- 
ure by passing the tube rapidly through an alcohol flame. 
Care must be taken to avoid breaking it. The metal 
cylinder is cleaned by unscrewing the bottom and removing 
the glass. In this way the cylinder can be easily and thor- 
oughly washed and dried. The cover-glasses should be 
kept in a solution of acid alcohol (see above). Before begin- 
ning a blood-examination a dozen or more of these cover- 
glasses should be cleaned with water, and then with alcohol, 
and dried ; then they should be passed through an alcohol 
flame and spread on a piece of paper. The cover-glasses 
should not be touched with the fingers after cleaning them, 
but should be handled with forceps. New cover-glasses are 
covered with an oily glaze which prevents the blood from 
spreading. Moisture from the fingers may alter the shape 
of the red blood-corpuscles. 

Never begin an examination of the blood until everything 
required for the entire examination is ready for use. A suf- 
ficient quantity of the diluting solutions must be poured into 
small dishes and placed, with the apparatus and cover- 
glasses, close at hand. If the preserving fluid contains a 
staining fluid, the solution must be filtered before using. 

To obtain the blood the part from which it is taken 
should be cleaned with soap and water, alcohol, and finally 
with ether, and thoroughly dried. The blood is usually ob- 
tained from the lobe of the ear or from the end of the finger. 
The ear possesses distinct advantages over the end of the 
finger. It is not necessary to hold the ear to prevent its 
withdrawal ; the operation is less painful, and the blood is 



360 PATHOLOGICAL TECHNIQUE. 

obtained more easily because the epidermis is thinner. These 
advantages are especially evident in infants and young chil- 
dren. In children it is almost impossible to keep the fingers 
extended without exerting pressure. Pressure on the part 
from which the blood is withdrawn must be avoided. It has 
been ascertained that moderately firm pressure on the finger 
is capable of diminishing the number of red corpuscles in a 
cubic millimeter by increasing the quantity of serum. The 
free border of the lobe of the ear is preferable to the anterior 
surface, because the border is convex. This is of advantage 
in making cover-glass preparations from small drops of 
blood. A narrow-bladed knife, similar to a tenotomy-knife, 
makes a relatively wide and shallow opening, and is prefer- 
able to a needle. 

The hemoglobin test must be performed in a dark 
room by means of a yellow light — lamp, gas, or candle light. 
Before obtaining the blood fill one of the divisions of the 
cylinder one-fourth full with distilled water ; then partly fill 
the pipette provided for this purpose, and place it close at 
hand ready to wash out any blood which may remain in the 
capillary tube, and thus prevent coagulation. The capillary 
tube is held horizontally, and touched slightly on the side of 
a freshly drawn drop of blood. The end of the tube should 
never be dipped deeply beneath the surface of a blood-drop. 
If the tube is perfectly clean and no coagulation has occurred 
in the drop of blood, the latter will instantly fill the tube. 
Sometimes it is necessary to slightly withdraw the end of 
the tube, without, however, permitting it to entirely leave 
the surface of the blood. Observe that the tube is exactly 
filled with blood and that the ends show neither convexity 
nor concavity. Any blood adhering to the end of the tube 
or to its outer surface must be quickly wiped off. Rapidly 
submerge the tube in the water and move it quickly to and 
fro several times, and with as little delay as possible wash 
out the remaining blood by means of the pipette. Fill the 
chamber three-fourths full with water and stir briskly with 
the metal handle of the capillary tube. Be careful to stir 
in the corners where the partition joins the sides. The blood 



HISTOLOGICAL METHODS. 36 1 

should be equally diffused throughout the fluid when the 
mixing has been well done, and there should be no coagula 
in it. When this has been done fill the cylinder to the level 
of the diaphragm ; the other division of the cylinder is then 
filled to the level of the diaphragm with distilled water. 
The surface of the fluid in each side must be perfectly flat. 
This can be readily ascertained by looking across the surface 
of the fluid with the eyes on a level with the top of the 
cylinder. A convexity or concavity of the water side can 
be easily obviated. A convexity on the side which contains 
the blood should be avoided. When the cylinder is in posi- 
tion, the division containing the distilled water is over the 
colored glass. The reflector should be arranged to throw as 
much light as possible when the percentage of hemoglobin 
is high ; but when the hemoglobin is much diminished, less 
light will give more exact results. To perform the test one 
eye should be closed and the face shielded from direct light 
by holding a piece of paper between the face and the lamp. 
The instrument should be arranged so that the observer 
stands at the side of it and looks directly down into the 
fluid. This is done so that the images of both divisions of 
the cylinder are thrown upon the retina side by side, and 
not one above the other. This permits a more accurate 
comparison of colors to be made. By means of the adjust- 
ment screw move the colored glass from a point where the 
glass is paler than the diluted blood to a point where the 
color of the glass and of the blood match. Then read the 
percentage on the scale, and control the result by moving 
the colored glass from above the point where the colors 
match downward, to see if the same result is obtained ; pause 
a moment and repeat the test. More accurate results are 
obtained by resting the eye several times than by looking 
for a long time. 

In order to estimate the number of red corpuscles 
in a cubic millimeter of blood it is necessary to use a dilut- 
ing fluid. It is desirable that this fluid should be of such a 
character that the corpuscles may not change their form or 
lose their color. Various fluids are used. Toison's fluid 



362 PATHOLOGICAL TECHNIQUE, 

possesses the advantage of staining the white corpuscles. 
The formula of this fluid is as follows : 



Distilled water, 


160 


c.c; 


Neutral glycerin, 


30 


<< 


Sodium sulphate, pur., 


8 


grams 


Sodium chlorid, 


1 


gram; 


Methyl-violet, 5 B, 


0.025 


a 



This fluid must be filtered each time before using. A drop 
of blood is required of sufficient size to more than fill the 
capillary tube of the " mixing pipette." If the drop is too 
small, it is difficult to prevent the entrance of air and coagu- 
lation of the blood in the tube in the interval of obtaining a 
second drop of blood. It is advisable, therefore, to perform 
this test before estimating the hemoglobin or making the 
cover-glass preparations. While filling the capillary tube of 
the pipette care must be exercised to keep the point of the 
pipette beneath the surface of the blood-drop to prevent the 
entrance of air. The blood is sucked up to the mark .5 or 
1., and then the tip of the tongue is pressed firmly over the 
hole in the mouth-piece. This prevents the blood-column 
from sinking or air from entering below while the tip of the 
pipette is being wiped and immersed in the diluting fluid. 
This part of the test requires the utmost precision and avoid- 
ance of delay. It is necessary, therefore, to keep the eyes 
constantly fixed on the capillary tube in order to note any 
variation in the blood-column. Rapidly wipe the tip of the 
pipette to remove the blood from the outside, and then im- 
merse the tip in the diluting fluid. Suck the fluid up to the 
mark 101, close the ends of the pipette with the thumb and 
middle finger, and shake the pipette for two minutes. If 
the ends of the pipette are not completely closed during this 
process, some of the fluid will escape. At the end of 
two minutes allow two drops to escape from the pipette 
before examination, because the fluid in the capillary tube is 
unmixed with blood. Then allow a drop to escape upon the 
central part of the counting slide. This drop should com- 
pletely fill the depression after the cover-glass has been 



HISTOLOGICAL METHODS. 363 

applied. A little practice is necessary in order to estimate 
the size of the drop required. A moderately thick cover- 
glass should be slid over or carefully laid upon the square 
raised surface, and pressure applied to the edges until the 
Newton color-zone can be seen between the cover-glass and 
the square raised surface beneath. Never press on the 
center of the cover-glass. Allow the blood-corpuscles to 
settle a minute or two before counting. 

The corpuscles are estimated as follows : One side of a 
small square is Y V mm - l° n g '■> tne enclosed square surface is 
■j-J-g- mm. The distance between the cover-glass and the 
disc is .1 mm. which gives a cubic capacity of 40V0 c - mm - 
for each square. To estimate the number of corpuscles in 
1 c.mm. of blood, multiply the number of corpuscles counted 
by 4000, and then by the number representing the amount 
of dilution, 1 00 or 200 as the case may be, and divide the 
result by the number of squares counted. 

Corp. X dilution X 4000 , 

c — corpuscles in 1 c.mm. 

Squares counted 

To avoid counting any of the corpuscles twice, always 
begin at the upper left-hand square of a quadrant and count 
four squares downward. Count all the corpuscles which 
touch the upper and left-hand lines of a square, together 
with the corpuscles in the square. Never count the cor- 
puscles touching the right-hand or lower double lines of a 
quadrant. In order to make an accurate count it is neces- 
sary to count at least 1 200 red corpuscles. 

If air-bubbles are present when the cover-glass is applied, 
it is necessary to clean the slide and use a fresh drop of the 
diluted blood. Before beginning the count examine the 
various quadrants with a low-power objective, to see if the 
corpuscles are evenly distributed. If they are not, it will be 
because the blood is not thoroughly mixed, and the slide 
should be washed and the pipette well shaken. Before ex- 
amining a second drop of the diluted blood shake the 
pipette for two minutes as before. The results of three 
drops should be averaged. 



364 PATHOLOGICAL TECHNIQUE. 

There is a special pipette for counting the white corpuscles, 
graduated so as to give a dilution of 1 to 10 or 1 to 20. 
The white corpuscles are estimated in the same way as the 
red corpuscles, except that the dilution 10 or 20 is sub- 
stituted for 100 or 200. This necessitates a fresh drop of 
blood. For a diluting fluid for counting the white corpuscles 
a i or 2 P er cent, solution of acetic acid may be used. This 
solution destroys the red corpuscles. A little gentian-violet 
solution may be added to the acetic acid if it is desired to 
stain the white corpuscles. 

It is possible to estimate both the white and red corpuscles 
in the same drop of blood quite accurately. In order to do 
this it is necessary to calculate the number of squares which 
would be contained in the entire ruled surface outside of the 
portion which is divided into quadrants. This may be done 
by means of a micrometer eye-piece and a movable stage. 
The number has been found to be about 2000, although 
there may be some slight variation in each slide. This enables 
one to count 50 white corpuscles or more in each drop by 
counting all the corpuscles within the lines. For calculating 
the number of corpuscles one would divide by the estimated 
number of squares counted, just as in determining the red 
corpuscles. The average of three drops gives quite accurate 
results and saves much time and trouble. 

The Elements of the Blood. — Red corpuscles, white 
corpuscles, and hematoblasts. The red blood-corpuscles 
(erythrocytes) are biconcave discs. The diameter of a red 
blood-corpuscle in human blood is the same for male and 
female, and averages 7.8 fi. The red corpuscles have a pale- 
yellow color with a faint tinge of green ; they are homo- 
geneous, highly refractive, and have no nuclei (normally). 
Outside the circulating blood the corpuscles rapidly undergo 
alterations in their shape and size. These changes may be 
prevented or hindered, for purposes of study, by appi opriate 
methods of fixation and preservation. The average number 
of red corpuscles in I cubic millimeter of human adult blood 
is from four million to five million. Under abnormal condi- 



HISTOLOGICAL METHODS. 365 

tions the red corpuscles vary in size, shape, and number, and 
a small proportion of them may have nuclei. 

1. Variations in the shape [poikilocytosis) are of frequent 
occurrence. Some of the corpuscles may be pear-shaped or 
bottle-shaped; others may be shaped like saddle-bags or 
have projections. Variations in the size of the erythrocytes 
are also common. They all retain the central depression, 
notwithstanding the variations in shape and size. 

2. Abnormally large erythrocytes, varying from 10 to 14// 
in diameter and without nuclei, are called megalocytes. Very 
small erythrocytes, varying from 2 to 5/i in diameter, are 
called microcytes. The microcytes contain hemoglobin, but 
do not have the central depression. 

3. Nucleated red corpuscles (erythroblasts) occur in two 
forms — the so-called normoblasts and the megaloblasts or 
gigantoblasts. A normoblast is the same size as a normal 
corpuscle, but contains a single relatively large nucleus. 
The nucleus is commonly situated in the center of the cor- 
puscle, but it may lie in the periphery, and takes a more 
intense stain than the nucleus of any other corpuscle. 
Mitosis is observed frequently. Free nuclei are found often. 
A megalo- or gigantoblast is from three to five times as 
large as a normal red corpuscle, and contains a relatively 
large round nucleus in the center. The intensity with which 
this nucleus stains is midway between that of the normo- 
blast nucleus and the nuclei of the white corpuscles. 

4. The so-called anemic degeneration of the red corpuscles 
is less commonly met with than the preceding changes. 
When cover-glass preparations are stained with eosin-hema- 
toxylin or eosin-methylene-blue, the red corpuscles, instead 
of staining a bright eosin-red, take a muddy-looking, darker 
stain. This appearance is assumed to be due to degenera- 
tive changes in the stroma of the corpuscles, which cause 
the hemoglobin to become stained to some extent by the 
nuclear stain in addition to the eosin. 

The white corpuscles (leucocytes) differ in size, in the size 
and shape of their nuclei, and in the granules which are con- 
tained in the protoplasm. They have been classified in vari- 



366 PATHOLOGICAL TECHNIQUE. 

ous ways, depending upon their supposed origin and upon 
the granules which they contain. 

Ehrlich differentiates five different kinds of granules found 
in the human blood : the a or eosinophilic granules ; the ft 
or amphophilic ; the o and y or basophilic granules ; and the 
£ or neutrophilic granules. 

The a or eosinophilic granules are coarse, round or oval, 
highly refractive granules which have an affinity for the acid 
aniline stains, especially eosin. 

The ft or amphophilic granules have an affinity for both 
acid and basic stains. They occur very rarely in human 
blood, but are common in the blood of certain animals. 

The o and y granules are finer and less refractive granules 
which have an affinity for basic stains. The y granules are 
nearly as large as the eosinophilic granules, but are not so 
refractive. The o granules are much finer and not very 
refractive, and are very numerous in the cells in which they 
occur. 

The e or neutrophilic granules are much smaller, more 
numerous, and less refractive than the eosinophilic granules, 
and have an affinity for neutral stains. They occur only in 
human blood. 

Morphologically, there are five varieties of white cor- 
puscles. They are — the small mononuclear cell or lympho- 
cyte ; the large mononuclear cell ; the transitional large 
mononuclear cell; the neutrophile; and the eosinophile. 
The small mononuclear cell or lymphocyte is slightly larger 
than a red corpuscle, and has a single round nucleus sur- 
rounded by a narrow strip of protoplasm which contains no 
granules. The nucleus stains more intensely than the nuclei 
of the other white corpuscles. 

The large mononuclear cell is much larger than the 
lymphocyte, and contains a large oval or round nucleus 
surrounded by a wide zone of protoplasm. The nucleus 
takes a fainter stain than that of the lymphocyte. 

The transitional large mononuclear cell differs from the 
large mononuclear only in having a saddle-bag-shaped 
nucleus. Variations in size are frequently observed in the 



HISTOLOGICAL METHODS. 367 

small mononuclear as well as in the large mononuclear cells, 
so that under some circumstances it is difficult to distinguish 
to which type of cell a given cell belongs. 

The neutrophile or polymorpho-nuclear leucocyte is about 
three times as large as a red corpuscle. This cell is the so- 
called polynuclear leucocyte found in pus. The nucleus, as 
the name implies, is more or less subdivided, and often re- 
sembles various letters, as S, Z, V, M, etc, The nucleus is 
surrounded by a relatively large amount of protoplasm 
which is more or less completely filled with fine neutrophilic 
granules. 

The normal eosinophile resembles the neutrophile in size 
and in the character of its nucleus. It differs from the 
neutrophile, at least chemically, by containing the eosino- 
philic a granules. 

The large mononuclear, transitional, and neutrophilic cells 
are regarded as the same cell in different stages of develop- 
ment. The younger form is the large mononuclear, and the 
oldest is the neutrophile. During the process of " ripening," 
as it is called, the fine e granules are formed in the proto- 
plasm, and the nucleus becomes more or less subdivided. 

The so-called masizellen — that is, cells which contain baso- 
philic granules — were supposed by Ehrlich to originate from 
fixed connective-tissue corpuscles and from the spleen, and 
not to be present normally in the blood. Later investiga- 
tions show that an occasional mastzelle may be found in 
normal blood. 

Markzellen, or myelocytes, is the name applied to large 
mononuclear cells containing neutrophilic, and sometimes 
eosinophilic, granules. These cells are present in the medul- 
lary cavity of the long bones, but are never found in the 
blood normally. 

Hematoblasts (Blut-plattchen) are small round or oval discs 
from 1.5 to 3.5 /i in diameter. They do not contain hemo- 
globin and have no central depression. They are so rapidly 
disintegrated on exposure to the air that it is necessary to 
use special precautions in order to preserve them. The best 
way to study them is to put a drop of some preserving fluid 



368 PATHOLOGICAL TECHNIQUE. 

on the skin from which the blood is to be obtained, and then 
puncture the skin through the fluid. A I per cent, aqueous 
solution of osmic acid can be used, or, if it is desired to 
stain them, I part of methyl-violet in 5000 parts salt solution 
may be used. 

Cover-glass Preparations. — The blood must be spread 
extremely and uniformly thin. If this is done, the blood 
dries very quickly, and the red blood-corpuscles retain their 
shape and are not crowded together and lying over one an- 
other. To obtain such a result it is essential that the cover- 
glasses should be absolutely clean ; that there should be no 
delay in bringing the cover-glass which has the drop of 
blood on its surface in contact with a second cover-glass ; 
and that the drop of blood should be quite small. The fol- 
lowing method gives the best results : The procedure is ren- 
dered much easier if some one is present to assist. This 
person places a finger beneath the lobe of the ear in order 
to raise it slightly without pressing upon it, and with a clean 
compress wipes away the blood as fast as it flows with a 
quick motion of the hand. This is done to prevent coagu- 
lation, which occurs very quickly, and prevents the drop of 
blood from spreading between the cover-glasses. It takes a 
little time for the blood to spread, the cover-glasses to be 
separated and laid down, and fresh ones picked up ; and if, 
during this time, some one wipes away the blood as fast as 
it flows, much better preparations are obtained. If, in spite 
of this, as often happens, the blood coagulates about the 
opening, one end of the compress can be slightly moistened 
with water and passed over the opening and the surface dried 
quickly. The blood then flows freely again. A drop of 
blood a little larger than a pin-head is sufficient. Grasp the 
edge of the cover-glass with a pair of spring forceps, pick up 
a second cover-glass with a pair of plain forceps. Both 
pairs of forceps must be especially prepared by having the 
inner surfaces of the points ground smooth. The cover-glass 
in the spring forceps is held horizontally just below the ear, 
and the other cover-glass, held with the other forceps, is 
touched lightly on the blood and immediately dropped on 



HISTOLOGICAL METHODS. 369 

the first one. If the cover-glasses are dry and clean and the 
blood has not begun to coagulate, it spreads at once in a 
thin film between the glasses. The glasses are then drawn 
apart with a rapid sliding motion by means of the forceps, 
waved in the air a few seconds, and laid down with the 
blood-surface uppermost. The layer of blood cannot be too 
thin, but it can easily be too thick. The cover-glasses 
should never be pressed together to make the blood spread. 
Considerable practice is required before one becomes pro- 
ficient. The specimens may be fixed by heat in a thermostat 
at a temperature between 1 io° and 120 C. (Ehrlich's 
method). This is objectionable on account of the time and 
apparatus required. A practical modification of this method 
is to heat the cover-glasses on a brass plate for an hour at a 
point on the plate where water boils. The plate should be 
about \ of an inch thick and from 15 to 18 inches long. It 
should be heated from one end to a constant temperature. 
Test the degree of heat with drops of water and select a 
part where the water boils. At a point nearer the flame it 
will be found that the water sputters and rolls about, indi- 
cating too high a temperature. After putting the cover- 
glasses, with the blood-side uppermost, upon the selected 
point, it is necessary to test the degree of heat from time to 
time, and perhaps to shift the cover-glasses. 

Methods of Staining. — Of the many staining fluids 
which have been employed to differentiate the white cor- 
puscles, it is necessary to mention only two, which have 
been found to answer all purposes. 

Ehrlich's Triple Stain. — The formula is as follows : 

Orange G, saturated aqueous solu- 
tion, 120 to 135 c.c. ; 
Distilled water, 100 " 

Acid fuchsin, saturated aqueous 

solution, 65 " 

Distilled water, 100 " 

Absolute alcohol. 100 " 



24 



370 PATHOLOGICAL TECHNIQUE. 

Methyl green, saturated aqueous 

solution, I2 5 ex.; 

Distilled water, 100 *' 

Absolute alcohol, ioo " 

Glycerin, ■ ioo " 

The various ingredients are prepared separately as indi- 
cated by the dotted lines, and are afterward mixed gradually. 
The mixture must stand for several weeks before using. It 
is advisable to withdraw by means of a pipette some of the 
staining fluid from the middle portion without disturbing the 
bottom. 

The cover-glass preparations should be stained from six 
to eight minutes, washed thoroughly with water, dried, and 
mounted in Canada balsam. The neutrophilic granules are 
stained violet ; the eosinophilic, a bright red ; the nuclei of 
the neutrophilic and the eosinophilic cells are a greenish- 
blue ; the nuclei of the lymphocytes, a deep blue ; the 
nuclei of the large mononuclear cells, a pale blue ; the red 
corpuscles, copper color; and the nuclei of the red cor- 
puscles, if any be present, a more intense blue than the 
nuclei of the lymphocytes. For some unexplained reason 
this stain is not always uniform in its action. 

It is sometimes difficult to distinguish a nucleated red cor- 
puscle from a lymphocyte. It is well to remember, there- 
fore, that the nuclei of red corpuscles stain more intensely 
than other nuclei, and have very sharply defined outlines, 
and by careful focusing it is seen that the surrounding 
stroma is stained the same color as the other red corpuscles. 

"Wright's Stain. — This staining fluid is an improvement 
on one devised by W. B. Leishman, because it requires only 
a few hours and an ordinary steam sterilizer for its prepara- 
tion, while Leischman's required at least eleven days and 
the employment of a thermostat regulated at 65 ° C. Leish- 
man deserves great credit for originating a method of stain- 
ing blood-films and malarial parasites which combines the 
important " Romanowsky " staining with the great advan- 



HISTOLOGICAL METHODS. 37 1 

tages of the methyl-alcohol method of Jenner. Wright's 
stain is applied in the same manner and gives the same 
results. 

It is preferred to Ehrlich's stain, because it does not 
require the difficult and uncertain fixation of the blood-film 
by heat and because it gives constantly satisfactory results 
even in the hands of inexperienced workers. 

This stain makes visible in the blood smear not only all 
that the Ehrlich's stain does, but more, for it gives the dif- 
ferential Romanowsky staining to mast-cells, blood-plates, 
certain degenerate products in the red corpuscles, and to 
malarial and other protozoan parasites, thus accomplishing 
at one and the same time all that which usually requires the 
employment of several special staining methods separately 
applied. 

It is prepared as follows : 

Dissolve 0.5 gm. of sodium bicarbonate in 100 c.c. of dis- 
tilled water, and add 1 gm. of methylene-blue (Grubler). 
Any of the methylene-blues of Grubler known as " BX," 
" Koch's," or " Ehrlich's Rectified " may be used. It seems 
to be important that the bicarbonate of soda be all dissolved 
before adding the methylene-blue. 

The mixture is next to be steamed in an ordinary steam 
sterilizer at ioo° C. for one hour, counting the time after 
" steam is up." The heating should not be done in a pres- 
sure sterilizer, or in a water-bath, or in any other way than 
as stated. This steaming of the alkaline solution of 
methylene-blue effects certain changes in the methylene- 
blue whereby a polychromatic property is given to it, so 
that the compound with eosin, which is later to be formed 
with it, has the property not only of differentially staining 
the chromatin of the malarial parasite, but also of differen- 
tiating and bringing out more sharply the nuclei and gran- 
ules of the white blood-corpuscles. 

When the steaming is completed, the mixture is removed 
from the sterilizer and allowed to cool, the flask being placed 
in cold water if desired. When it is cold, without filtering, 
pour it into a large dish or flask, and add to it, stirring or 



37 2 PATHOLOGICAL TECHNIQUE. 

shaking meanwhile, a sufficient quantity of a I : iooo solu- 
tion of eosin (Grubler, yellowish, soluble in water) until the 
mixture, losing its blue color, becomes purple in color, and 
a scum with yellowish metallic luster forms on the surface, 
while on close inspection a finely granular black precipitate 
appears in suspension. This will require about 500 c.c. of 
the eosin solution for 100 c.c. of the alkaline methylene-blue 
solution. These are quantities which are convenient and 
suitable to employ. 

The precipitate is collected on a filter, and, without wash- 
ing, is allowed to dry thereon. When thoroughly dry, dis- 
solve this precipitate in pure methyl-alcohol in the proportion 
of 0.5 gm. to 100 c.c. of alcohol. This alcoholic solution is 
the staining fluid. It is not necessary to filter it. It will 
keep indefinitely, as will also the dry precipitate. Precau- 
tions should be taken to prevent the alcohol from evapo- 
rating, for thus the solution may become too saturated and 
precipitates may form on the blood-film in the process of 
staining. If the staining fluid deposits such precipitates, it 
should be filtered and a small quantity of methyl-alcohol 
added to it. 

Method of Staining Blood-films. — The films of blood, 
which should be spread thinly, are allowed to dry in the air. 
When dry, as much of the staining fluid is poured upon a 
film as the cover-glass will readily hold without draining off 
Allow the staining fluid to remain in contact with the film 
for one minute. This chiefly serves the purpose of fixing 
the blood-corpuscles. The cover-glass is most conveniently 
manipulated by means of cover-glass forceps. 

Next add to the staining fluid on the cover-glass distilled 
water, drop by drop, until a delicate scum with iridescent 
metallic luster forms on the surface. The amount of water 
required will vary with the amount of staining fluid on the 
preparation, but, in general, it may be said that six or eight 
drops will be required if a seven-eighth inch square cover- 
glass is used. The amount of water added must not be 
sufficient to make the fluid transparent. 

The staining fluid, thus diluted, is allowed to remain 



HISTOLOGICAL METHODS. 373 

on the preparation for two or three minutes, during which 
time the real staining of the preparation takes place and is 
then washed in water. 

The blood-film will now be seen to have a blue or purple 
color, and if examined with the microscope, the red blood- 
corpuscles will be seen to be stained blue. 

The next step is to develop the differential staining of the 
various elements in the preparation. This is done by wash- 
ing the preparation in water — preferably distilled water — 
until the better spread portions of the film appear yellowish 
or reddish in color. Some tap waters may spoil the staining. 
If desired, the process of differentiation may be readily 
observed by placing the cover-glass film side uppermost on 
a slide, covering it with water, and examining it with the 
microscope under a low magnifying power. The red blood- 
corpuscles, which, as before stated, at first have a blue color, 
will become greenish, then yellowish, and finally orange or 
pinkish in color, depending upon the depth of the original 
staining, which varies with the length of time that the 
diluted staining fluid has been allowed to act and with the 
degree of its dilution. 

The differentiation by washing in water seems to be essen- 
tially a process of decolorization by which some of the blue 
constituent of the dye is removed, for the water that drains 
off from the preparation has a blue color. This differentia- 
tion or decolorization proceeds slowly, and may require one 
or more minutes, depending upon the intensity of the stain- 
ing and upon the tint sought to be obtained in the red cor- 
puscles. 

It is apparent from the above that with a little experience 
with the method the color of the red corpuscles may be 
made either orange or pink, as the operator desires. When 
the desired color is obtained in the red corpuscles, the 
preparation is then quickly dried between layers of filter- 
paper and mounted in balsam. It is important to stop the 
decolorization by drying the preparation as soon as the 
desired tint in the red corpuscles is obtained, for it mny be 
carried too far. 



374 PATHOLOGICAL TECHNIQUE. 

Dried stain on the upper surface of the cover-glass may 
be easily removed with ordinary alcohol. 

In the light of the foregoing explanations the following 
summary of the method of staining blood-films will be 
intelligible : 

i. Make films of the blood, spread thinly, and allow them 
to dry in the air. 

2. Cover the preparation with the staining fluid for one 
minute. 

3. Add to the staining fluid on the preparation sufficient 
water, drop by drop, until a delicate, iridescent, metallic 
scum forms on the surface. Allow this mixture to remain 
on the preparation for two or three minutes. 

4. Wash in water, preferably in distilled water, until the 
film has a pinkish tint in its thinner or better-spread portions 
and the red corpuscles acquire a yellow or pink color. 

5. Dry between filter-paper and mount in balsam. 

The preparations retain their colors as long as any prepa- 
rations stained with aniline dyes. 

Unstained blood-films may be kept for some weeks with- 
out impairment of their staining properties. Films months 
old will probably not give good results. 

Microscopical Appearances in Blood-films Stained with 
Wright's Stain. — The red cells are orange or pink in color. 
Polychromatophilia and punctate basophilia or granular 
degeneration are well brought out. The nucleated red cells 
have deep-blue nuclei, and the cytoplasm is usually of a 
bluish tint. 

The lymphocytes have dark purplish-blue nuclei and 
robin's-egg-blue cytoplasm in which a few dark-blue or 
purplish granules are sometimes present. 

The polynuclear neutrophilic leucocytes have a dark-blue or 
dark lilac-colored nucleus, and the granules are usually of 
a reddish-lilac color. 

The eosinophilic leucocytes have blue or dark lilac-colored 
nuclei. The granules have the color of eosin, while the 
cytoplasm in which they are imbedded has a blue color. 

The large mononuclear leucocytes appear in at least two 



HISTOLOGICAL METHODS. 37$ 

forms. Each form has a blue or dark liiac-colored nucleus. 
The cytoplasm of one form is pale blue and of the other 
form is blue with dark-lilac or deep-purple-colored granules, 
which are usually not so numerous as are the granules in 
the polynuclear neutrophilic leucocytes. 

The mast-cells appear as cells of about the size of poly- 
nuclear leucocytes with purplish or dark-blue stained, 
irregular-shaped nuclei, and with cytoplasm, sometimes 
bluish, in which numerous coarse spherical granules of 
variable size are imbedded. These granules are of a dark- 
purple color and may appear almost black. 

The myelocytes have dark-blue or dark lilac-colored nuclei 
and blue cytoplasm in which numerous dark-lilac or red- 
dish-lilac-colored granules are imbedded. In leukemia more 
color differences are brought out among the leucocytes than 
by the ordinary methods of staining. 

The blood-plates are well stained. In the best preparations 
they appear as round or oval, very pale blue bodies with 
smooth contour, containing many small dark-lilac or blue 
stained granules. In many instances, however, only the 
deeply stained granules in their substances are visible. 
They are usually of a diameter of one-third to one-half of 
that of a red blood-corpuscle. Frequently they occur in 
groups or masses, and at first sight may be regarded as 
precipitates. 

METHODS OF FIXING AND EXAMINING SPECIAL 
ORGANS AND TISSUES. 

Tissues which are to be hardened should be obtained as 
fresh as possible. For this reason autopsies rarely furnish 
such perfect material as is obtainable from experimental 
lesions in animals or from surgical operations. Still, most 
of the pathological material comes from autopsies, and it is 
encouraging to know that very good work can often be done 
with tissues not fixed until twenty-four hours or even more 
after death. The most valuable autopsies are those which 
are freshest, and in which but one etiological factor has been 
concerned, so that the relation between the cause and the 



376 PATHOLOGICAL TECHNIQUE, 

lesion produced is uncomplicated and can be readily grasped 
and understood. 

The choice of the proper fixing reagent varies with the 
tissue, the lesion, and the use to which the material is to be 
put. For simple diagnosis alcohol is usually sufficient. For 
special investigations other fixatives may be required. In 
general it may be said that alcohol is best suited for bacteria 
and for many micro-chemical color reactions ; Zenker's or 
Orth's fluids for red blood-globules, nuclear figures, and 
protoplasm ; formaldehyde for the central nervous system. 
More attention will be paid to this point in the consideration 
of the separate organs and tissues. 

It is important that pieces of tissue for histological study 
should be placed in the proper fixative as soon after the 
removal of the organs from the body as possible, so that the 
surface will not dry or the blood and other fluids escape 
from the vessels. Do not wash off the surface with water. 
The tissues should almost invariably be cut into thin slices, 
not over 4 to 8 mm. thick. For the finer fixatives, 2 mm. 
should not be exceeded. 

Frozen sections of fresh tissues will often show whether 
the material is worth saving, and suggest what fixatives had 
best be used — such as Flemming's solution, for instance, if 
fat is present. 

Acute Inflammatory Exudations ; Granulation- 
tissue. — The elements in acute inflammatory exudations 
which require preservation are chiefly polynuclear leucocytes, 
serum, fibrin, and red blood-globules. The best general 
fixative for them all is Zenker's fluid. It not only pre- 
serves perfectly the characteristic nuclei of the leucocytes, 
but also the protoplasm, which stands out sharply in con- 
trast-staining with eosin. The albumin of the serum is 
coagulated into a finely granular material. The fibrin and 
red blood-globules stain brilliantly with eosin. Alcohol is 
generally preferred for the fixation of any organisms asso- 
ciated with the exudation, but after fixation in Zenker's fluid 
they can be perfectly stained with Unna's alkaline methylene- 
blue solution. Occasionally other fixatives, such as Flem- 



HISTOLOGICAL METHODS. 377 

ming's or Pianese's, will be found useful, especially for the 
study of any attendant degenerations. 

Zenker's fluid will also be found invaluable for fixing 
granulation-tissue where a similar exudation is generally 
combined with new-formed blood-vessels and connective 
tissue. It also permits the use of the aniline-blue connective- 
tissue and the fibroglia stains. 

For the study of the plasma-cells which early make their 
appearance in granulation-tissue hardening in alcohol is 
generally advisable, although Zenker's fluid is often to be 
preferred, and for eosinophiles is indispensable. 

I/Ung". — In the preservation of the lungs it is important 
to save portions that have not been squeezed, so that the 
relations of the exudations may not have been changed or 
the alveoli compressed. Thin slices are usually preferable 
to cubical pieces, and should be cut with a very sharp knife, 
so as not to compress the tissue, and dropped immediately 
into the fixing fluid, before the contents of the bronchi and 
of small cavities have had time to run out. An emphysem- 
atous lung is so delicate that it is usually better to inject a 
whole lung through the bronchi with the fixing fluid or to 
snip out small pieces with scissors. Zenker's fluid and 
alcohol are the most useful fixatives. 

Spleen. — The spleen-pulp may be examined by means 
of dried cover-slip preparations in the same way as described 
for the blood. Material can be obtained immediately after 
death by means of a long trocar thrust into the spleen. 
Teased preparations can be examined in salt solution. The 
spleen-tissue is well preserved in Zenker's fluid if cut into 
thin slices not over 2 to 4 mm. thick. Paraffin sections are 
to be preferred when convenient, so that the thinnest possi- 
ble sections may be obtained. Stain by the eosin methylene- 
blue method. 

Bone -marrow may be examined in the same way as 
spleen-pulp in cover-slip preparations, or thin slices may be 
hardened in Zenker's fluid or some other fixative, such as 
formaldehyde, for study by means of sections. Eosin followed 
by alkaline methylene-blue solution is strongly advised. 



37§ PATHOLOGICAL TECHNIQUE. 

For cover-slip preparations Wright's blood-stain gives 
excellent results. 

Kidney. — The choice of fixing reagents varies largely 
with the lesions present. Zenker's fluid is advisable for 
general histological purposes, for blood, and for hemo- 
globin ; alcohol for bacteria, amyloid, hemosiderin ; Flem- 
ming's for fat; boiling water for albuminous exudations. 
The pieces of tissue preserved should include both cortex 
and pyramids. 

In cases of chronic nephritis the capsule should not be 
peeled from those parts kept for microscopical purposes. 

Paraffin imbedding is generally to be preferred for the 
kidney, especially when lesions of the glomeruli are present. 

For the simple demonstration of fat, teased preparations 
or frozen sections of fresh material can be mounted in water 
and treated with acetic acid or stained in sudan III. 

Gastrointestinal Tract. — Portions of the stomach or 
intestine should be hardened as soon after death as possible 
for satisfactory study, because the gastro-intestinal tract so 
rapidly undergoes post-mortem changes. It has been recom- 
mended in appropriate cases, where an autopsy is allowable, 
to inject the stomach with the desired fixing solution by 
means of a rubber tube as soon after death as is permissible. 
Under no circumstances should the surface of the intestine 
or stomach be washed with water. Use either normal salt 
solution or some of the fixing solution. It is important to 
keep the tissue flat while hardening. This can usually be 
done by laying it with the peritoneal surface down on thick 
filter-paper, to which it readily sticks. Sometimes it is 
necessary to pin the specimens down at the edges on flat 
pieces of cork. Do not let the surface dry before the speci- 
men is placed in the fixing solution. Zenker's fluid can be 
highly recommended as a fixative, but alcohol is sometimes 
to be preferred. 

I/iver. — For fat the liver is examined fresh in teased 
preparations or frozen sections, or after hardening in Flem- 
ming's or Marchi's solution, by means of celloidin or paraffin 
sections. 



HISTOLOGICAL METHODS. 379 

For obtaining the iron reaction with hemosiderin in cases 
of pernicious anemia, and for the reactions of amyloid, 
harden in alcohol. 

For general histological study Zenker's fluid will be found 
exceedingly useful. 

The bile-capillaries may be demonstrated by means of 
Golgi's silver method. 

Boehm's directions for it are as follows : 

1. Harden pieces of liver 1 cm. in diameter for seventy 
hours or more in 

3 per cent, solution of bichromate of potassium, 4 parts; 
1 per cent, solution of osmic acid, 1 part. 

2. Transfer for twenty-four to forty-eight hours to a f- per 
cent, solution of nitrate of silver. 

3. Wash in water. 

4. Harden and cut. 

The bile-capillaries appear dark brown on a yellow ground. 

Bone and CaTrtilage. — Excellent work can be done after 
hardening in alcohol, and fixation in it is generally recom- 
mended for all infectious processes in bone. The histological 
structure is, however, better preserved in Zenker's or Orth's 
fluid. In decalcifying bone, after proper fixation, thin pieces 
should be taken, not more than 2 to 4 mm. thick, so that the 
process may be finished as quickly as possible. While tu- 
bercle bacilli will stain readily after being twenty-four or even 
forty-eight hours in 5 per cent, nitric acid, it is impossible 
to stain them after they have been subjected to the same 
strength of nitric acid for four days. (For details in regard 
to decalcification see page 267.) 

Celloidin is preferable to paraffin for imbedding. Besides 
a simple stain with alum-hematoxylin, double stains of the 
latter with neutral carmine or eosin are sometimes advanta- 
geous. The best pictures with carmine as the contrast-stain 
are obtained by staining first in alum-hematoxylin, washing 
twelve to twenty-four hours, and then staining in the neutral 
carmine. The carmine stains decalcified bone and osteoid 
tissue red. Phosphotungstic-acid hematoxylin will some- 



380 PATHOLOGICAL TECHNIQUE. 

times be found useful, especially when cartilage is present, 
because it stains the intercellular substance, both of bone and 
of cartilage, pink, while the nuclei are stained blue. The 
ground substance of cartilage, especially in new-growths, 
often stains so intensely with alum-hematoxylin that the 
nuclei are quite obscured. For the same reason chlorid of 
iron hematoxylin is often useful because it does not stain the 
ground substance. 

The following method is recommended for differentiating 
cartilage from bone : 

Schaffer's Safranin Method. — Decalcify with nitric acid. 

1. Stain sections a half to one hour in an aqueous solution 
of safranin, 1 : 2000. 

2. Wash in water. 

3. Place for two to three hours in a -^ per cent, solution 
of corrosive sublimate. 

4. Examine in glycerin, or, if permanent specimens are 
desired, pass very quickly through alcohol, blot with filter- 
paper, further dehydrate, and clear for a long time in berga- 
mot or clove oil, and mount in xylol balsam. This is a 
double stain : cartilage, orange ; bone, uncolored ; connective 
tissue and marrow, red. 

None of the methods above given has proved reliable in 
the study of rickets and of osteomalacia for differentiating 
osteoid from true bone-tissue. In important cases, therefore, 
it is advisable to use an old knife, and to cut sections of the 
undecalcified tissue after imbedding thoroughly in celloidin. 

SchmorTs methods 1 of demonstrating the lacunae and 
canalicular of bone in sections can be highly recommended. 

Method A. — 1. Fix, preferably in Muller's fluid, formal- 
dehyde, or Orth's fluid ; do not use corrosive sublimate 
solution. 

2. Decalcify by the slower methods — namely, Ebner's or 
Thoma's, or in Muller's fluids 100 c.c. plus nitric acid 3 c.c. 

3. Imbed in celloidin ; paraffin is objectionable. 

4. Place the sections for at least ten minutes in water to 
get rid of the alcohol. 

1 Schmorl : Centralblatt filr allg. Pathologie, 1899, x., 745. 



HISTOLOGICAL METHODS. 38 1 

5. Stain for five to ten minutes or longer in saturated solu- 
tion of thionin in 50 per cent, alcohol, 2 ex., water, 10 c.c., 
or in Nicolle's carbolthionin solution. 

6. Wash in water. 

7. Place in a saturated aqueous solution of picric acid for 
one-half to one minute. 

8. Wash in water. 

9. Place in 70 per cent, alcohol for about five to ten min- 
utes until no more dense clouds of color are given off. 

10. Dehydrate in 95 per cent, alcohol. 

11. Clear in oleum origani cretici. 

12. Xylol balsam. 

Bone substance yellow to yellowish-brown ; bone lacunae 
and canalicular dark brown to black ; cells red. Fat-cells 
after fixation in Miiller's fluid reddish violet. Osseous tissue 
stains a deeper yellow than osteoid tissue. Canalicular stain 
in osseous tissue, but not in osteoid tissue unless the thionin 
solution is made alkaline by the addition of 1 or 2 drops of 
ammonia. (This solution cannot be recommended for gen- 
eral use.) 

This method is not a true stain, but resembles Golgi's 
method ; a precipitation of coloring-matter takes place in 
the lacunar and canalicular ; it also takes place to a consid- 
erable extent in other narrow spaces in the tissues, and often 
is very disturbing. It can be gotten rid of to some extent 
without injury to the stain by leaving the sections in step 8 
in the water for half an hour. The canalicular are now 
usually brownish red to red, and the bone substance blue 
to colorless. In this case it is often best to stain the sec- 
tions first in alum hematoxylin to bring out the nuclei. 

Method B gives good results with the bones of children 
only. 1. Harden in Miiller's fluid or in Orth's fluid, fol- 
lowed by Miiller's for six to eight weeks, or for three to four 
weeks in the thermostat ; take very thin pieces of tissue. 

2. Wash off in water, and decalcify in Ebner's solution. 

3. Wash thoroughly in running water. 

4. Harden in alcohol ; imbed in celloidin ; cut sections 
very thin. 



382 PATHOLOGICAL TECHNIQUE. 

5. Stain in Nicolle's carbolthionin, or better in the alkaline 
(NH 4 OH) thionin solution given above, for three minutes. 

6. Transfer to a saturated aqueous solution of phospho- 
tungstic or phosphomolybdic acid (use glass or platinum 
needle) for a few seconds or longer. The sections become 
blue, green, or gray in color. 

7. Water five to ten minutes until they acquire a sky-blue 
color. 

8. Place in dilute ammonia (1-10) for three to five minutes 
to fix the color. 

9. Transfer directly to 90 per cent, alcohol ; change sev- 
eral times to get rid of the ammonia. 

10. 96 per cent, alcohol. 

11. Clear in carbol xylol. 

12. Xylol balsam. 

If the ground-substance is stained too deeply by the alka- 
line thionin solution, treat the sections with acid alcohol for 
five minutes, followed by water before dehydrating. The 
borders of the lacunae and canalicular stain bluish black ; 
the ground-substance of bone clear to greenish blue ; cellu- 
lar elements a diffuse blue color. In rachitic bones the 
canalicular are brought out only in osseous tissue. 

Skin. — Much of the material for the study of lesions of 
the skin is obtained during life by means of a Mixter punch 
or with the knife or scissors. Fixation in absolute alcohol 
is often advisable, especially when it is desired to stain bac- 
teria, mastzellen, plasma-cells, and elastic fibers. The stain- 
ing methods for these tissue-elements will be found on 
pages 320-328. For Unna's innumerable stains for degen- 
erated connective-tissue fibers, elastic fibers, etc., the reader 
is referred to his numerous articles on technique in the 
Monatshcft f. prakt. Dermatologic during the last half-dozen 
years. 

For many skin-lesions, especially those in which blood- 
vessels play a more or less prominent part, Zenker's fluid is 
advisable. For finer histological work Pianese's fixatives and 
special stains are recommended. 

In the examination of hairs or scales of epidermis for 



HISTOLOGICAL METHODS. 383 

bacteria and fungi it is important first to remove the fat from 
them by means of equal parts of alcohol and ether. They 
are then examined in 40 per cent, caustic potash, which, by 
clearing up the cells, brings out the organisms and spores 
quite distinctly. Heating the potash over a small flame 
hastens the process, but is a somewhat risky proceeding ; 
soaking in the solution over night is better. Examine the 
preparation with most of the light excluded. 

Preparations may be made in certain cases by touching the 
cover-slip to the surface of the lesion, drying, and passing 
through the flame. After removing the fat by means of 
alcohol and ether, stain as with ordinary cover-slip prepara- 
tions. 

Unna's method is to rub up the scales of epidermis in a 
little glacial acetic acid between two slides, which are then 
drawn apart and quickly dried over the flame. After re- 
moving the fat by means of alcohol and ether the slide 
preparations are stained in borax-methylene-blue. 

For staining the various vegetable parasites of the skin 
Malcolm Morris recommends the following method, which 
he claims is the best one yet devised, as it avoids the use of 
the hydrate of potash : 

1. Ether or alcohol and ether equal parts. 

2. Stain in a solution of 5 per cent, gentian-violet in 70 
per cent, alcohol, five to thirty minutes. 

3. Iodin solution, one minute. 

4. Aniline, or aniline plus 2 to 4 drops of nitric acid. 

5. Aniline. 

6. Xylol. 

7. Xylol balsam. 

The most suitable medium for the growth of the various 
ringworms is the following, due to Sabouraud : 

Agar-agar, i-SO; 

Peptones, .50; 

Maltose 3.80 ; 

Water, 100. 



384 PATHOLOGICAL TECHNIQUE. 

Instead of test-tubes, Erlenmeyer flasks are used, so as 
to get a large flat surface for the growth to spread over from 
the point of inoculation in the center. The most favorable 
temperature for growth is 30 C. 

Museum Preparations. — Specimens intended to be 
preserved for the museum should generally be gotten into 
pretty good shape by trimming and dissecting before they 
are placed in the hardening reagent. Of the liver or other 
large organs and tumors, sections several centimeters thick 
are generally preferable to the whole specimen. The usual 
custom in the past has been to wash the specimen for a 
number of hours or over night in running water, to get rid 
of the blood, and then to preserve in 80 per cent, alcohol. 
This method preserves form and relations well, but is nearly 
valueless for preserving colors. 

Since the introduction oi formaldehyde, from which at 
first much was expected in the way of faithful fixation of 
the normal colors of gross preparations, numerous attempts 
have been made to improve on the results obtainable with 
formaldehyde alone. Of the methods advocated, the follow- 
ing from Virchow's laboratory seems the most promising, 
and can be highly recommended : 

Kaiser ling-' s Method of Preserving* the Natural Colors 
in Museum Preparations. — 1. Fixation for one to five days 
in — 

Formaldehyde, 200 c.c. ; 

Water, 1000 " 

Nitrate of potassium, 1 5 grams ; 

Acetate of potassium, 30 " 

Change the position of the specimen frequently, using rubber 
gloves to protect the hands from the injurious effect of the 
formaldehyde. The time of fixation varies with the tissue 
or organ and size of the specimen. 

2. Drain and place in 80 per cent, alcohol one to six 
hours, and then in 95 per cent, alcohol for one to two hours, 
to restore the color, which is somewhat affected in the 
fixing solution. 



HISTOLOGICAL METHODS. 385 

3. Preserve in — 

Acetate of potassium, 200 grams ; 

Glycerin, 400 c.c. 

Water, 2000 " 

Exposure to light gradually affects the colors. The 
process of fixation should be performed in the dark, and the 
specimens when preserved should be kept in the dark except 
when on exhibition. 

If it seems desirable to cut a thin slice from the face of a 
specimen, this should not be done until the preparation has 
been in the preservative fluid two weeks. The specimen 
may then be placed in alcohol for one to two hours to 
brighten up the colors. 

PATHOLOGICAL PRODUCTS. 

Cloudy Swelling; Albuminous Degeneration. — 

The increase in the relative number of the albuminous 
granules of the protoplasm of the various tissue-cells in 
pathological processes is usually determined by examination 
of the fresh material, either macroscopically from the appear- 
ances on section, or microscopically from teased preparations 
or frozen sections mounted in salt solution. The organ as a 
whole (and therefore the individual cells) usually shows 
some increase in size. The nucleus is generally more or 
less obscured if the process is at all marked. According to 
Israel, the cloudiness must be recognizable with low powers 
and in places where the cells are massed together. The 
diagnosis should not be based on the appearances of single 
cells. 

The chemical properties of the albuminous granules are 
the following : they disappear on treatment with dilute acetic 
acid (1-2 per cent, solution usually) ; they are not dissolved 
by chemical substances which dissolve fat (absolute alcohol, 
ether, chloroform, etc.) ; and they do not stain with osmic 
acid. The acetic-acid test is the one usually employed. 

Albuminous degeneration can also be studied in sections 

25 



386 PATHOLOGICAL TECHNIQUE. 

of tissues hardened in certain of the fixatives and stained 
with diffuse colors. For this purpose hardening in Zenker's 
fluid and staining in eosin and methylene-blue or in alum- 
hematoxylin and eosin can be highly recommended. 

Fat. — This term includes a variety of fat-like substances, 
of which the three most common and important in the 
animal kingdom are olein, palmitin, and stearin, the glycerin- 
ates of oleic, palmitic, and stearic acids. Under certain con- 
ditions the free fatty acids themselves and their lime-salts 
may be present. Among the fat-like substances belongs 
also the myelin of the nerve-sheaths. The pigments of the 
ganglion-cells and of many other cells contain fat, and hence 
react like fat, but the fat and the pigment can be separated. 

These various forms of fat differ somewhat in their reac- 
tion to certain reagents used as tests. They are all insoluble 
in dilute acids and alkalies, but are soluble in strong alcohol, 
in ether, and in chloroform. Osmium tetraoxid is reduced 
by olein and oleic acid, by myelin, and the fat in certain pig- 
ments, but is not reduced by the palmitic and stearic com- 
ponents of body-fat unless the tissue after exposure to the 
osmium tetraoxid is placed in dilute alcohol ; if placed in 
strong alcohol, the reduction takes place imperfectly or not 
at all. Myelin differs from the other fat substances in that 
it can be fixed by a chrome salt so that it will no longer 
reduce the osmium tetraoxide. 

Scharlach R. is the strongest of a group of fat stains of 
which Sudan III. has, perhaps, been the most used until 
recently. These stains have the common property of dis- 
solving readily in all fats, including myelin and the lipo- 
chrome of ganglion-cells. The staining, which is purely 
physical in nature, depends simply on the fact that fat is a 
better solvent of the stain than the alcohol is, and takes it 
up from it. 

The common tests for fat are the three following : As all 
these fatty substances are unaffected (at least not for some 
months) by formaldehyde, it is becoming more and more 
customary to apply the tests, especially the Scharlach R. 
stain, to frozen sections after fixation in that reagent. 



HISTOLOGICAL METHODS. 387 

1. Acetic Acid. — The test may be applied to teased 
preparations or to frozen sections. The acetic acid is gener- 
ally employed in a 1 or 2 per cent, solution, of which a few 
drops are placed at the edge of the cover-slip and drawn 
under by means of a bit of filter-paper placed at the oppo- 
site edge. 

2. The Osmium Stain for Pat. — A 1 per cent, solution 
may be applied like the acetic-acid test to teased prepara- 
tions or to frozen sections. It is more usual, however, to 
fix very thin sections (not over 1 mm. thick) in a I per cent, 
solution of osmium tetraoxid for one to three days, or, 
better still, in a combined solution, such as Flemming's or 
Marchi's, containing it. 

Flemming's solution should be allowed to act from two to 
four days if the tissue is from 2-3 mm. thick, and then the 
pieces of tissue should be thoroughly washed in running 
water for twenty-four hours before being placed for several 
days in dilute and then in strong alcohol. 

Marchi's method was intended for differentiating fat from 
myelin (see page 267), but the solution employed by him 
may be used for staining fat in ordinary tissues. Place small 
pieces of tissue in it for five to eight days, wash thoroughly 
in running water, and place in dilute (50 to 70 per cent.) 
alcohol for several days before transferring to strong alcohol. 

Marchi's method, carried through in the manner just de- 
scribed, succeeds perfectly with tissues fixed in formaldehyde. 

Osmium reduced by fat is soluble in ether, turpentine, 
xylol, and toluol, but is not dissolved by alcohol, chloro- 
form, or oil of cloves. Imbedding in celloidin is not contra- 
indicated, as the alcohol probably protects the osmium from 
the injurious action of the ether. For the paraffin method 
clear in chloroform, and mount in properly prepared chloro- 
form balsam (see page 300). 

3. The Scharlach R. (or Sudan III.) Stain for Fat. — 
Cover-slip Preparatiotis. — 1. Fix five to ten minutes in the 
vapor of formaldehyde. 

2. Stain in a saturated filtered solution of Scharlach R. or 
Sudan III. for fifteen to twenty minutes. 



388 PATHOLOGICAL TECHNIQUE. 

3. Wash quickly in 50 per cent, alcohol to transfer to 
water or place the section directly from the stain into water. 

4. Counterstain with alum-hematoxylin or methylene-blue. 

5. Mount in glycerin. 

Sections. — 1. Place frozen sections of fresh or formalde- 
hyde-hardened material in 50 per cent, alcohol for a few 
seconds only. 

2. Stain in Scharlach R. for fifteen minutes to overnight. 

3. Wash quickly in 50 per cent, alcohol. 

4. Wash in water. 

5. Counterstain in alum-hematoxylin. 

6. Mount in glycerin. 

For the surest results omit the alcohol both before and 
after the stain. The staining should always be done in a 
tightly stoppered bottle, because with any evaporation of 
the alcohol a precipitation of the staining material immedi- 
ately takes place. 

Herxheimer recommends the following solution as stain- 
ing much more quickly — two to five minutes. 

Absolute alcohol, 70; 

10 per cent, solution of sodium hydrate, 20; 

Water, 10. 

Scharlach R. to the point of saturation. 

Benda's Stain for Fat Acid Crystals. — In a solution of 
copper acetate the crystals of the free fatty acids and of the 
fatty acid salts of lime stain blue. Benda recommends fixa- 
tion in Weigert's copper-fluorchrom-acetic-acid-mordant plus 
10 per cent, of formalin for two to four days at 37 C. 
Frozen sections are then to be cut, counterstained in Schar- 
lach R. and alum-hematoxylin, and mounted in glycerin. 

Cholesterin crystals are recognized by their shape. On the 
addition of concentrated sulphuric acid the crystals turn 
yellow and then rose-color. Treated with a little iodin, fol- 
lowed by concentrated sulphuric acid, they become colored 
violet, changing gradually to blue, green, and red. 

Necrosis. — Necrosis in tissues is generally recognized by 



HISTOLOGICAL METHODS. 389 

two features : either by the disappearance of the nuclei, al- 
though the cell-outlines may be visible, so that the nuclear 
stain is no longer possible, or by the presence of irregular, 
larger or smaller masses, generally supposed to be due to a 
fragmentation or breaking-up of the chromatin, which stain 
intensely with nuclear stains. The disappearance of the 
nucleus is not synchronous with the death of the cell, but 
begins some twenty-four hours later, so that it is really evi- 
dence of changes following necrosis. It follows from the 
above that the microscopic evidence of necrosis is best 
studied in sections of tissues hardened in fixatives which 
favor nuclear staining, such as alcohol, Zenker's fluid, etc. 
Teased preparations and frozen sections of fresh tissue are 
much less useful. 

For the study of sections from hardened material double 
stains with alum-hematoxylin and eosin, or, still better, with 
eosin followed by Unna's alkaline methylene-blue solution, 
are very useful, for the reason that the necrotic areas usually 
stain rather deeply with the diffuse stain, and are thereby 
brought out sharply. 

For rendering the fragmented nuclei prominent the same 
methods may be followed as for mitosis. A fuchsin stain 
washed out by picric acid in the alcohol will often give 
excellent results. 

Caseation is probably a tissue-change following local 
necrosis. Macroscopically and microscopically it resembles 
harder or softer cheese. Under the microscope it appears 
as coarsely or finely granular masses which have more or 
less completely lost the original tissue-structure. The chemi- 
cal changes which have taken place have not been studied. 
Fibrin is rarely present. Caseous tissue possesses no pe- 
culiar staining reactions. Fragmented nuclei are frequently 
present in it, especially in the peripheries of the areas. 

Pibrin. — Fibrin usually appears as delicate, transparent, 
slightly refractive threads which are often closely matted 
together so as to form large masses. More rarely it appears 
as coherent masses of the finest granules, as homogeneous 
glassy lumps, or as thin sheets. The characteristic reaction 



390 PATHOLOGICAL TECHNIQUE. 

for fresh fibrin is that it quickly swells up and optically dis- 
solves in very dilute acetic acid. 

Fibrin is well brought out in sections of hardened tissues 
by a double stain of alum-hematoxylin and eosin, or of eosin 
followed by Unna's alkaline methylene-blue solution, espe- 
cially if the specimens have been fixed in Zenker's fluid. 

Weigert's Differential Stain for Fibrin. — i. Harden in 
alcohol. Good results can also usually be obtained after 
Zenker's fluid. 

2. Stain sections in lithium carmine (see page 313). 

3. Stain in Weigert's aniline-methyl-violet three seconds. 

4. Wash off with normal salt solution. 

5. Weigert's iodin solution a few seconds. 

6. Wash off with water. 

7. Decolorize in aniline oil and xylol equal parts. 

8. Wash off with three changes of xylol. 

9. Xylol balsam. 

To stain sections fixed in formaldehyde or in a chrome 
salt, place them in a \ per cent, aqueous solution of per- 
manganate of potassium for ten minutes, wash in water, and 
reduce in a 5 per cent, aqueous solution of oxalic acid for 
two to three hours or longer. Then wash thoroughly in 
water. 

The fibrin and those bacteria which are stained by Gram 
are stained blue. The nuclei are red if the decolorization is 
carried far enough. It can easily be watched under the low 
power of the microscope. The method is not always suc- 
cessful, especially with tissues which are old. Besides the 
fibrin, certain forms of hyaline are often stained by this 
method. 

Differential stains for fibrin are also obtained by the chlo- 
rid of iron hematoxylin stain (page 311) and by the con- 
nective-tissue stain (page 322). The former is applicable 
after any fixing reagent, the latter only after Zenker's fluid. 

The phosphotungstic-acid-hematoxylin method is also 
useful if all the steps are followed out as for neuroglia fibrils. 

Mucin. — The term " mucin " is applied to a proteid sub- 
stance having certain chemical reactions, and also to certain 



HISTOLOGICAL METHODS. 39 1 

other substances which give the same reactions, but do not 
belong to the proteids. These various substances of secre- 
tory and degenerative origin cannot be distinguished micro- 
scopically, and have been investigated but little chemically. 
The reactions in common are the following : they dissolve 
in water to form a slimy fluid ; they are precipitated from 
slightly alkaline solutions by acetic acid ; the fresh precipi- 
tate dissolves in alkalies and in neutral salt solutions. Acetic 
acid, usually employed for this purpose in a I or 2 per cent, 
solution, precipitates mucin in the form of threads or gran- 
ules. This reaction with fresh tissues has long been the 
main test for mucin. The acetic acid is drawn under the 
cover-slip by means of filter-paper placed at the opposite 
edge. The preparation should be mounted in water, not in 
salt solution, which may hinder or entirely prevent the reac- 
tion from taking place. Of late certain color reactions have 
become prominent. Mucin is coagulated into threads by 
alcohol or corrosive sublimate, and in this form can be 
stained by a number of staining reagents. Alum-hema- 
toxylin under certain conditions will stain mucin. Accord- 
ing to P. Mayer, these conditions depend on a certain degree 
of ripeness of the solution, on the presence of enough alum 
to keep the nuclei from staining deeply, and, most important 
of all, on the absence of any free acid. This is difficult to 
manage, unless the solution is carefully neutralized, on ac- 
count of the acid properties of alum. Mayer therefore 
recommends staining the sections in muchematein (see page 

283). 

Various aniline dyes have been recommended for staining 
mucin : those most favorably spoken of are methylene-blue 
(Orth), Bismarck brown (P. Mayer), thionin (Hoyer), poly- 
chrome methylene-blue (Unna), and toluidin-blue. The 
drawback to most of the aniline stains is that they are 
quickly extracted by the alcohol used for dehydrating. On 
this account P. Mayer highly recommends Bismarck brown, 
because permanent mounts can be easily made with it. It 
is not extracted by alcohol, and it does not fade in Canada 
balsam like many of the others. 



39- PATHOLOGICAL TECHNIQUE. 

Hardening in corrosive sublimate and imbedding in par- 
affin are generally recommended as preferable to hardening 
in alcohol and imbedding in celloidin. Stain sections for 
five to fifteen minutes in a rather dilute aqueous solution of 
the dve chosen. Of Bismarck brown use a saturated aque- 
ous solution, and stain, if necessary, twenty-four hours. 
With thionin, toluidin-blue, and polychrome methylene-blue 
metachromatic stains are obtained ; the mucin is colored red, 
the rest of the tissue blue. Two special methods for stain- 
ing mucin are given in detail : 

Hoyer's Thionin Stain. — Mucin, red ; everything else, 
blue. I. Harden in corrosive sublimate, followed by alcohol. 

2. Paraffin sections are passed through xylol, chloroform, 
and 95 per cent, alcohol to free them from paraffin, and are 
then placed in a 5 per cent, aqueous solution of corrosive 
sublimate for three to five minutes. 

3. Stain in a dilute solution of thionin for ten to fifteen 
minutes. 

4. Alcohol. 

5. Clear in the mixture of the oils of cloves and thyme. 

6. Turpentine oil or oil of cedar. 

7. Balsam. 

Before the staining the sections must not be treated with 
iodin solution to get rid of the precipitate of mercury, be- 
cause it spoils the staining. 

Unna's Polychrome Methylene-blue Stain. — 1. Stain 
paraffin or celloidin sections hardened in alcohol in poly- 
chrome methylene-blue five to ten minutes or longer. 

2. Wash in acidulated water. 

3. Fix in 10 per cent, solution of bichromate of potassium 
half a minute. 

4. Wash in water. 

5. Dry on slide with filter-paper. 

6. Decolorize in aniline plus 1 per cent, hydrochloric acid 
(a few seconds only). 

7. Wash off with oil of bergamot. 

8. Balsam. 

Pseudo -mucin dissolves in water to form a slimy 



HISTOLOGICAL METHODS. 393 

material, and is precipitated from its solutions by alcohol in 
thread-like masses which are again soluble in water. It is 
not affected by acetic acid. Pseudo-mucin is found in cer- 
tain ovarian and other tumors. 

Colloid and Hyaline. — The terms colloid and hyaline 
are not yet sharply limited to definite chemical substances. 
The term colloid was originally applied to the homogeneous 
substance found in the thyroid gland, but has been broad- 
ened to include various substances of a similar appearance. 
The term hyaline is still more indefinite, but its use may be 
said to be applied most generally to those homogeneous 
substances which stain deeply with various stains, in contra- 
distinction to those which, like colloid, show no marked 
affinity for staining reagents after ordinary fixatives. 

Unquestionably, numerous substances of different chemi- 
cal composition and of varying origin have been grouped 
under these two titles because of their physical and optical 
characteristics — namely, that they occur as glassy, refractive, 
homogeneous, occasionally colored gelatinous or firm masses. 
Chemically, very little that is definite is known about them, 
and they possess no peculiar chemical reactions. Several at- 
tempts have been made to classify them in accordance with 
their reactions to various staining reagents. 

Von Recklinghausen applied the term colloid to all the 
homogeneous, transparent-looking substances, including mu- 
cin, amyloid, etc., and reserved the term hyaline for a special 
group, which, according to him, is characterized by the fol- 
lowing peculiarities : it resembles amyloid in physical charac- 
teristics, but does not react to iodin ; it stains deeply with 
acid dyes, such as eosin and acid fuchsin. 

Ernst has recently endeavored to differentiate two groups 
of hyaline substances, colloid and hyaline, by means of their 
reaction to Van Gieson's picro-acid fuchsin solution. Ac- 
cording to him, true hyaline stains with acid fuchsin alone, 
and appears of a deep-red color, while colloid, of which the 
typical example is found in the thyroid gland, stains with 
both picric acid and acid fuchsin, so that it appears of an 
orange or yellowish-brown color. He has also tried to 



394 PATHOLOGICAL TECHNIQUE. 

prove that all colloid is derived from epithelial cells, while 
all hyaline comes from connective tissue or from blood- 
vessels. 

According to Von Kahlden, these differential staining re- 
actions with Van Gieson's mixture claimed by Ernst for col- 
loid and hyaline are by no means justifiable, because true 
colloid often stains a deep red. Furthermore, Unna has 
shown that in the skin connective-tissue cells can give rise to 
the so-called true hyaline, of which part is acidophilic and 
part basophilic, while the intercellular substance gives rise to 
colloid. 

The last attempt to classify the various homogeneous sub- 
stances on the basis of their reactions to dyes, apparently 
the only method possible at present, has been made by 
Pianese as a result of his studies of the various degenerative 
processes occurring in cancer-cells. He used a special fixa- 
tive (see p. 262) and five different staining methods (see p. 
293, methods III. A and B, IV., V., and VI.). Of these 
methods, III. B. is the best, because it gives a characteristic 
color to each substance — hyaline, brick-red ; colloid, bright 
green ; mucin, clear sky-blue ; and a substance resembling 
amyloid, a dark reddish-violet. Besides these distinct re- 
actions for colloid, hyaline, mucin, and a substance resem- 
bling amyloid, he found others less definite ; one of these he 
calls pseudo-mucin and another pseudo-colloid. As a basis 
for his studies he took the reactions of amyloid, mucin (in- 
testine), colloid (thyroid gland), and hyaline (hyaline remains 
of ovarian follicles, hyaline degeneration of renal glomeruli), 
with the same stains after fixation in his own hardening 
mixture. 

The above brief historical statement is considered neces- 
sary to show the present views in regard to these various, 
more or less indefinite, homogeneous, transparent substances. 
For demonstrating them after the usual hardening reagents, 
of which alcohol and corrosive sublimate are perhaps the 
best, a double stain with alum-hematoxylin and eosin is very 
useful. Certain of the homogeneous substances stain deeply 
with eosin ; others, like the transparent drops and masses 



HISTOLOGICAL METHODS. 395 

occasionally found in the walls of the blood-vessels of the 
brain, stain with hematoxylin. Sometimes good results can 
be obtained with Weigert's fibrin stain or with carbol-fuch- 
sin. The most generally useful stain, aside from alum-hema- 
toxylin and eosin, is probably Van Gieson's mixture. 

1. Stain deeply in alum-hematoxylin. 

2. Wash in water. 

3. Stain three to five minutes in a saturated aqueous solu- 
tion of picric acid, to which is added enough of a saturated 
aqueous solution of acid fuchsin to give it a deep-red color. 
The effect of various proportions is sometimes useful. 

4. Wash in water. 

5. Alcohol. 

6. Oleum origani cretici. 

7. Balsam. 

The transparent homogeneous substances usually stain 
from orange to deep red in color ; connective tissue, red. 

Unna's Method for Hyaline and Colloid Material. — A. 
Harden in alcohol. 1. Acid fuchsin (2 per cent, aqueous 
solution) five minutes. 

2. Saturated aqueous solution of picric acid two minutes. 

3. Saturated alcoholic solution of picric acid two minutes. 

4. Wash off in alcohol. 

5. Oil, balsam. 

Hyaline and connective-tissue fibers, red ; colloid of thy- 
roid gland, yellow ; protoplasm, yellow. 

B. To show acidophilic and basophilic hyaline : 1 . Water- 
blue (2 per cent, aqueous solution), twenty to thirty seconds. 

2. Water. 

3. Carbol-fuchsin one to two minutes. 

4. Water. 

5. Alcohol slightly tinged with iodin. 

6. Pure alcohol. 

7. Oil, balsam. 

Nuclei, keratin, and large hyaline masses, cherry red ; con- 
nective-tissue fibrillae, protoplasm, and small hyaline bodies, 
blue. 

For finer work the methods of Pianese should be used. 



396 PATHOLOGICAL TECHNIQUE. 

Keratohyalin (Unna). — 1. Stain sections in a fairly old 
alum-hematoxylin solution until they are over-stained. 

2. Place in a very weak solution of permanganate of 
potassium (about 1 : 2000) for ten seconds. 

3. Dehydrate and decolorize in alcohol. 

4. Oil, balsam. 

An isolated stain of the granules of keratohyalin is ob- 
tained, blue-black in color. 

In like manner a 33 per cent, solution of sulphate of iron 
acting for ten minutes, or a 10 per cent, solution of chlorid 
of iron for a few seconds, will produce the same effect. Or- 
dinarily, sections are stained deeply in alum-hematoxylin, 
and decolorized with acetic acid and alcohol or with hydro- 
chloric acid and alcohol. 

Glycogen. — Glycogen is a carbohydrate of slightly vary- 
ing composition, occurring in cells, more rarely in the inter- 
cellular tissue, either diffusely or more commonly in the 
form of larger and smaller masses and granules of a trans- 
parent homogeneous appearance. It is demonstrated micro- 
chemically by means of its reaction with iodin, which stains 
it brown. It is easily differentiated from amyloid by the 
fact that with the exception of the glycogen from certain 
sources, such as cartilage-cells, it is readily soluble in water 
and does not give the iodin-sulphuric-acid reaction. 

In consequence of its property of dissolving readily in 
water the aqueous Lugol's solution of iodin cannot be em- 
ployed for staining glycogen in fresh tissues. Instead, a thick 
solution of gum arabic containing t per cent, of Lugol's 
solution must be used, or, better still, equal parts of glycerin 
and Lugol's solution, in which the sections are more perfectly 
cleared. 

For sections hardened in absolute alcohol the same 
methods may be used, but better results, and practically 
permanent mounts, can be obtained by the method of Lang- 
hans. Lugol's solution is used for staining the sections, be- 
cause after hardening in alcohol the glycogen is much less 
soluble in water than in the fresh state. The iodin-glycerin 
mixture would probably be better. 



HISTOLOGICAL METHODS. 2)97 

1. Langhans' Iodin Stain. 

i. Stain paraffin sections in Lugol's solution. 

2. Dehydrate in I part of tincture of iodin to 3 or 4 parts 
of absolute alcohol. 

3. Clear in oleum origani cretici. 

The sections are to be preserved in oil. Even a ring of 
balsam around the cover-slip will cause the color to fade. 
Other oils are not so good. 

2. Lubarsch's Iodin-Hematoxylin Stain. 

1. Fixation in absolute alcohol. 

2. Stain paraffin sections for five minutes in the following 
solution, which should be filtered and carefully protected 
from sunlight : 

Delafield's hematoxylin, 2 ; 

Lugol's solution, 2 ; 

Water, I. 

3. Absolute alcohol, xylol, xylol balsam. 

4. Expose to daylight one to two days. Glycogen brown, 
nuclei blue. 

Lubarsch's Gentian- violet Stain. — Alcohol fixation ; 
paraffin imbedding. 

1. Stain with Meyer's alcoholic carmine solution, differen- 
tiate in acid alcohol, wash off in absolute alcohol. 

2. Stain in aniline oil gentian-violet for one to two minutes, 
warming slightly if necessary. 

3. Wash quickly in water. 

4. Gram's solution of iodin on section continuously for 
five to ten seconds. 

5. Dry thoroughly with filter-paper. 

6. Dehydrate and differentiate in aniline-oil xylol (2 to 1) 
or in pure aniline oil. 

7. Wash thoroughly in xylol and mount in balsam. 
Nuclei red ; glycogen dark blue to violet. It is advisable 

to expose the sections to daylight for one to two days. The 
preparations will keep up to one year. 



398 PATHOLOGICAL TECHNIQUE. 

Best's Carmine Stain. 

Carmine, I ; 

Chlorate of ammonium, 2 ; 

Carbonate of lithium, 50. 

Boil for a moment only ; after cooling, add 20 c.c. of 
liquor ammonii caustici. The solution stains best after two 
or three days and keeps for several weeks in the dark. 

1. Stain celloidin sections first in Delafield's hematoxylin 
(an intense stain is desired). 

2. Stain for one hour in the following mixture, freshly 
prepared, which must not be filtered. 

The above carmine solution (freshly fil- 
tered), 2 ; 
Liquor ammonii caustici, 3 ; 
Methyl-alcohol, 6. 

3. Decolorize for ten to twenty minutes in frequent changes 
of either one of the following solutions : 

Methyl-alcohol, 2 ; 

Absolute alcohol, 4 ; 

Water, 5. 



Or 



Liquor ammonii caustici, I ; 

Absolute alcohol, 2. 



4. Wash off in 80 per cent, alcohol. 

5. Alcohol, oil, balsam. 

Lubarsch recommends this method as by far the best of 
all stains for glycogen. Nuclei blue ; glycogen red. 

Amyloid Infiltration. — Amyloid is insoluble in water, 
alcohol, ether, and dilute acids, and is not digested by pepsin 
and hydrochloric acid. It is distinguished from the other 
homogeneous substances, except glycogen, by the fact that 
it is stained mahogany-brown by iodin in solution. If a 
section containing amyloid be quickly and lightly stained in 
iodin solution and then transferred to sulphuric acid, the 
color of the amyloid will usually change at once or in a few 
minutes from red, through violet, to blue. Sometimes the 



HISTOLOGICAL METHODS. 399 

color turns simply of a deeper brown. Several of the 
aniline dyes give almost as perfect characteristic color reac- 
tions for amyloid as iodin, and are perhaps better for the 
purposes of histological study. Any of these differential 
stains may be used with fresh or hardened tissues. Alcohol 
as a hardening reagent gives the best results, but the other 
fixatives may be employed. Unfortunately, good permanent 
mounts cannot be made with any of the characteristic stains, 
so that the ordinary double stains of alum-hematoxylin with 
eosin or Van Gieson's mixture will often be found of the 
greatest help in studying the distribution of amyloid. 
The aniline-blue connective-tissue stain can also be highly 
recommended because it stains amyloid light blue, so that 
it stands out in marked contrast to the red of the liver- 
cells. 

Iodin Reaction for Amyloid. — 1. Stain sections in a weak 
solution of iodin (Lugol's solution diluted until of a clear 
yellow color) for three minutes. 

2. Wash in water. 

3. Mount and examine in water or glycerin. 

If the tissue reacts strongly alkaline, a condition which 
may result from post-mortem decomposition, the color reac- 
tion with iodin will not take place. In such cases the tissue 
or the sections of it should be treated with dilute acetic acid 
before applying the test. The normal reaction of amyloid 
with iodin may be increased by treating the section after 
staining with dilute acetic acid. 

Langhans' Method for Obtaining" Permanent Mounts 
with Iodin. — 1. Harden in alcohol and stain in Mayer's alco- 
holic carmine solution. 

2. Stain sections in Lugol's solution five to ten minutes. 

3. Dehydrate quickly in 1 part of tincture of iodin to 3 or 
4 parts of absolute alcohol. 

4. Clear and mount in oleum origani cretici. 

The color is said to keep remarkably well. Other oils or 
balsam cause it to fade quickly. The staining in Lugol's 
solution may be omitted, as the tincture of iodin usually 
stains the amyloid sufficiently deeply. 



400 PATHOLOGICAL TECHNIQUE. 

Iodin and Sulphuric-acid Reaction. — i. Stain quickly 
and lightly in dilute Lugol's solution. 

2. Treat with sulphuric acid, either concentrated or dilute 
(i to 5 per cent), on the slide or in the staining dish. Strong 
hydrochloric acid may be used in the same way. 

The change of colors from red to blue already spoken of 
usually occurs within a few minutes, but occasionally does 
not take place at all. 

The following substances give reactions with the above 
iodin tests : 

i. Ciiolesterin crystals are stained rather dark with dilute 
iodin solution, and turn a beautiful blue color at the edges 
on the addition of strong sulphuric acid. 

2. The corpora amylacea in the prostate and central 
nervous system stain brown with the dilute iodin solu- 
tion. 

3. Starch-granules stain blue with dilute iodin solution. 

4. Cellulose stains yellow with iodin. If washed and 
treated with strong sulphuric acid, it turns blue where the 
acid touches it. 

For the reactions with the aniline dyes the sections must 
be free from celloidin. 

Reaction "with Methyl- or Gentian-violet. — 1. Stain in 
I per cent, methyl-violet three to five minutes. 

2. Wash in water plus 1 per cent, of hydrochloric acid. 

3. Examine in water or in glycerin. 

The stain will keep for some time if mounted in a satu- 
rated solution of acetate of potash or in levulose. Other 
methods are to stain in aniline-gentian-violet and to wash 
out in a I or 2 per cent, solution of acetic acid, or to stain 
in a strong solution of methyl-violet to which acetic acid is 
added, and to wash out in water. The amyloid is stained 
violet-red, the tissue blue. 

Reaction "with Iodin-green. — 1. Stain fresh or hardened 
sections in a J- per cent, aqueous solution of iodin-green for 
twenty-four hours. 

2. Wash in water. 

3. Mount in water or glycerin. 



HISTOLOGICAL METHODS. 4OI 

Amyloid, a violet-red ; tissue, green. Stilling claims that 
the reaction is surer than with methyl-violet. 

Reaction with Bismarck Brown and Gentian-violet 
(Birch-Hirschfeld). — 1. Stain in a 2 per cent, alcoholic solu- 
tion of Bismarck brown five minutes. 

2. Wash in absolute alcohol. 

3. Wash in distilled water ten minutes. 

4. Stain in a 2 per cent, solution of gentian-violet five to 
ten minutes. 

5. Wash in dilute acetic-acid solution. 

6. Mount in levulose. 
Amyloid, red ; tissue, brown. 
Mayer's Stain for Amyloid. 

1. Transfer paraffin sections without previous treatment 
directly from the knife to a warmed (40 C.) half per cent, 
aqueous solution of gentian-violet for five to ten minutes. 

2. Wash in water and differentiate in a 1 per cent, solu- 
tion of acetic acid for ten to fifteen minutes. 

3. Wash thoroughly in water. 

4. Transfer to a half concentrated aqueous solution of 
alum. Wash off in water. 

5. Transfer sections to slide and allow the water to evapo- 
rate. 

6. Remove paraffin and clear with xylol. Mount in xylol 
balsam. 

Pigmentation. — The various pigments found in the 
human body under normal and pathological conditions may 
be divided into three groups : 

1. Hematogenous pigments, derived from the coloring 
matter of the blood. 

(a) Hemoglobin and mctlicmoglobin : soluble in water and 
alcohol, not absolute ; occur as yellowish to yellowish-brown 
granules and droplets ; stain deeply with eosin after proper 
fixation ; occur in hemoglobinuria, etc. 

(b) Parhemoglobin : a form of hemoglobin ; crystallizes 
like it, but is insoluble in alcohol. 

(c) Hcmatoidin=bilirubin : contains no iron ; is insoluble 
in water, alcohol, and ether ; dissolves in chloroform ; occurs 

26 



402 PATHOLOGICAL TECHNIQUE. 

as yellow or brown amorphous material or as crystalline 
rhombic plates and needles. Is found in extravasations of 
blood. 

(d) Hemosiderin : occurs as bright-colored, yellowish- 
brown and brown granules and masses ; gives iron reac- 
tion ; is insoluble in water, alcohol, and ether ; is found 
in extravasations of blood, in the liver in pernicious 
anemia, etc. 

(e) Melanin : occurs as dark-brown or black granules and 
masses ; does not give iron reaction ; is found in malaria in 
the red blood-globules and in the tissues of the spleen, liver, 
and brain, but not of the lungs. 

(/) Bile-pigment=bilimbin=hematoidin : insoluble in water, 
ether, and alcohol ; occurs as yellowish granules and masses 
which are often greenish if old ; is found in jaundice. 

2. Autochthonous pigments, formed by cells from color- 
less elements of nutrition. They all occur microscopically as 
lighter or darker brown granules ; are insoluble in water, 
alcohol, dilute caustic potash, etc., and contain no iron. 
Many of them are combined with fat, and hence seem to give 
some of the reactions for fat. They are found in the iris, 
retina, skin, ganglion-cells, Addison's disease, melanotic sar- 
comata, etc. 

3. Extraneous pigments, entering the body from with- 
out. The most common examples are carbon in anthra- 
cosis pulmonum, iron in siderosis pulmonum, silver in 
argyria. 

Pigments are recognized microscopically, partly by their 
color and form, partly by their chemical reactions, and partly, 
though less accurately, by the lesions or pathologic proc- 
esses in connection with which they occur. They usually 
show best in contrast to red nuclear stains, such as alum or 
lithium carmine, but alum-hematoxylin often gives excellent 
results. 

The pigments of the second and third groups are perfectly 
preserved by all the ordinary fixatives, of which alcohol, 
corrosive sublimate, and Zenker's fluid can be particularly 
recommended. Of the first group, melanin and hematoidin 



HISTOLOGICAL METHODS. 403 

are preserved in any fixative. Hemoglobin and methemo- 
globin must be fixed in the solutions recommended for red 
blood-globules — namely, Zenker's fluid, corrosive sublimate, 
and Miiller's fluid. Parhemoglobin and hemosiderin should 
be preserved in alcohol. Bile-pigment is turned green, accord- 
ing to Ziegler, by fixation in corrosive sublimate, and is 
thereby rendered more prominent. In alcohol it preserves 
its yellow color. 

Carbon may be distinguished from melanin or any of the 
other pigments by the fact that it is insoluble in concentrated 
sulphuric acid. The only pigment for which micro-chemical 
color reactions are generally employed is hemosiderin, which 
really represents a group of pigments containing iron instead 
of one definite compound. Most of them will show the iron 
reaction after a shorter or longer time, but others, like the 
hemoglobin from which they are all derived, refuse to give it. 

The iron compounds present are usually ferric salts, but 
occasionally ferrous. Both groups react in the same way 
to sulphate of ammonium, but only the ferric salts react to 
ferrocyanid of potassium. For the ferrous salts, which 
occur much more rarely, the ferricyanid of potassium must 
be used. Dr. E. S. Wood suggests that a mixture of ferro- 
and ferricyanid of potassium be employed, so as to demon- 
strate at once both groups of iron compounds, as with the 
sulphate-of-ammonium method. In performing the iron 
reactions steel needles must be avoided. 

Reactions for Iron in Hemosiderin. — Tissues should be 
hardened in alcohol. I. Reaction for ferric salts with ferro- 
cyanid of potassium and hydrochloric acid. 

A. 1. Place sections for five to twenty minutes or longer 
in a 2 per cent, aqueous solution of ferrocyanid of potas- 
sium. 

2. Transfer to acid alcohol (HC1 I c.c. to 70 per cent, 
alcohol 100 c.c.) for five to ten minutes, or to glycerin plus 
\ per cent, hydrochloric acid. The iron appears bright blue 
in color. 

If desired, the sections can be washed out after the acid 
alcohol, and passed through alcohol and oil to balsam. 



404 PATHOLOGICAL TECHNIQUE. 

After the iron reaction has been performed, the nuclei may 
be stained in either alum or lithium carmine, or a little ferro- 
cyanid of potassium may be added to the lithium carmine, 
and the reaction and nuclear stain thus effected by the same 
step. 

B. H. Stiedds Method for Permanent Mounts with Nuclear 
Stains. — i. Stain several hours in lithium carmine. 

2. Wash off quickly in water. 

3. Place from four to six hours in a 2 per cent, aqueous 
solution of ferrocyanid of potassium. 

4. Transfer to acid alcohol for six to twelve hours. 

5. Wash quickly in water. 

6. Alcohol, oil, Canada balsam. 

II. The reaction for the ferrous salts is performed in the 
same way as for ferric salts, with the exception that ferri- 
cyanid of potassium is used instead of the ferro- compound. 

III. Reactions for Ferric and Ferrous Salts. — A. Use a 
mixture of ferro- and ferricyanid of potassium (1 gram each 
to 100 c.c. of water), followed by acid alcohol. Nuclear 
stains and permanent mounts may be made as above. 

B. 1. Place sections in a freshly prepared solution of sul- 
phate of ammonium for five to twenty minutes, until they 
are dark or black-green in color. 

2. Wash quickly in water. 

3. Examine in glycerin or pass through alcohol and oil to 
Canada balsam. 

The iron appears in the form of black or dark-greenish 
granules. Sulphate of ammonium causes similar precipi- 
tates with other metal salts, such as the nitrates of silver, 
lead, and mercury. 

Petrifaction. — Calcification, the more common form of 
petrifaction, is the term applied to the infiltration of tissues 
with phosphate and carbonate of lime. The salts appear 
microscopically as small, very refractive granules which may 
be mistaken for fat, or as large masses due to the fusion of 
granules. They are dissolved by hydrochloric or nitric acid 
(5 per cent, solution). If carbonate of lime is present, bubbles 
of carbon dioxid are set free. Phosphate of lime dissolves 



HISTOLOGICAL METHODS. 405 

without effervescence. To differentiate between lime-salts 
and other substances soluble in hydrochloric acid use con- 
centrated sulphuric acid to form sulphate of lime (gypsum), 
which appears as fine, short, radiating needles. On dissolv- 
ing out the lime-salts a matrix of dead tissue or of hyaline 
material will usually be found left behind. As a rule, this 
hyaline material stains deep blue in alum-hematoxylin or red 
in Van Gieson's mixture. 

Another form of petrifaction is that found in gout, due to 
the infiltration of certain tissues with uric-acid salts, of which 
urate of sodium is the most common. The crystals are sol- 
uble with difficulty in cold water, insoluble in alcohol and 
ether. 



THE STAINING OF BACTERIA IN TISSUES. 

Bacteria are demonstrated in sections of tissues almost 
entirely by means of the aniline dyes, of which three have 
thus far proved themselves to be particularly valuable — 
namely, methylene-blue, gentian-violet, and fuchsin. These 
dyes are employed in aqueous or dilute alcoholic solutions, 
of which the effective staining power is greatly increased by 
means of heat and by the addition to the solutions of certain 
chemical substances. 

The effect of moderate heat is obtained by placing the 
sections in the incubator for several hours, or greater heat 
for a short time is utilized by warming the staining solution 
on the slide over a small flame for a few seconds or minutes, 
keeping the fluid steaming, but not allowing it to boil. 

Of the various methods employed to increase the staining 
power of aniline dyes by means of chemical substances, the 
most successful have been the use of caustic potash with 
methylene-blue, of aniline oil with gentian-violet and fuchsin, 
and of carbolic acid with fuchsin and methylene-blue. 

For decolorizing sections after they have been stained, the 
most commonly employed reagents are — 

1. Acetic acid in dilute aqueous solutions, 1 : 100, 1 : 1000. 

2. Alcohol. 



406 PATHOLOGICAL TECHNIQUE. 

3. Iodin in iodid-of-potash solution (with certain dyes only). 

4. Mineral acids in various strengths. 

5. Chlorid of aniline. 

6. Acid aniline colors added to the alcohol to increase its 
extractive power. 

7. Aniline and ethereal oils. 

The choice of a decolorizer varies with the staining solu- 
tion employed and with the organism that is to be stained. 

Sections which are to be stained for bacteria may be di- 
vided into two classes : 

1. Sections free from celloidin, subdivided into — 

a. Sections cut without an imbedding mass ; 

b. Paraffin sections ; 

c. Sections from which the celloidin has been removed. 

2. Sections infiltrated with celloidin. 

Celloidin imbedding is to some extent a drawback to the 
stains for certain organisms, because the celloidin tends to 
hold the color, so that the bacteria are not so distinct as they 
otherwise would be. Still, it is so important to be able to 
stain bacteria in celloidin sections that particular care is de- 
voted in the following pages to methods which obviate most 
of the difficulties. 

Paraffin sections should, as a rule, be attached to the slide 
by means of Mayer's glycerin-albumin mixture. 

It will usually be found advisable to attach celloidin sec- 
tions to the slide by means of ether-vapor. They will then 
keep perfectly flat in any staining solution, and may be heated 
without danger of wrinkling or contracting. The heat should 
never be applied directly under a section, but at one end of 
the slide. 

All bacteria yet known will stain when placed in appro- 
priate staining solutions. Some, however, are stained quickly, 
while others are stained with difficulty ; some give up the 
stain readily to decolorizers, while others retain it tena- 
ciously. In consequence of their reactions to certain dyes 
and to certain decolorizers, bacteria, from the point of view 
of staining, may be divided into three groups : 
1. Bacteria which do not stain by Gram; 



HISTOLOGICAL METHODS. 407 

2. Bacteria which stain by Gram ; 

3. Bacteria which stain by the tubercle bacillus method. 
Two at least of the organisms in the third group will also 

stain by Gram. The organisms of the second and third 
groups are much more easily demonstrated in tissues than 
those in the first group, because it is possible to stain them 
of one color and the nuclei of the cells of another color. In 
other words, it is possible to stain them so that they are 
differentiated from the tissue in which they lie, and hence 
stand out prominently. 

The organisms of the first group have no differential stain ; 
they take the same color as the nuclei of the tissue. More- 
over, although they stain easily, most of them do not stain 
deeply, and readily part with the color they have taken up. 

Pathogenic Bacteria which do not Stain by Gram. 

(See page 94.) 

Of these organisms certain ones deserve special mention 
on account of their frequent occurrence or on account of the 
difficulty of demonstrating them in tissues, and certain varia- 
tions in staining methods which have proved serviceable will 
be given. Loffler's methylene-blue solution is generally 
considered the most useful stain for this class of bacteria, 
but excellent results can also be obtained with Unna's alka- 
line methylene-blue solution preceded by eosin, especially 
after fixation in Zenker's fluid. 

Loffler's Methylene-blue Stain for Bacteria. — 1. Stain 
paraffin sections twenty minutes to twenty-four hours. 

2. Wash in weak acetic acid, 1 : 1000, for ten to twenty 
seconds. 

3. Absolute alcohol, two or three changes, to differentiate 
and dehydrate (as a rule, only a few seconds are required for 
this step). 

4. Xylol. 

5. Xylol balsam. 

For celloidin in sections use 95 per cent, alcohol ; blot, 
and treat with xylol ; repeat until sections are clear ; mount 
in xylol balsam. 



408 PATHOLOGICAL TECHNIQUE. 

This solution of methylene-blue is extremely useful, be- 
cause it will stain all bacteria except the tubercle-bacillus 
group. Other solutions which may be used in the same way 
are — aniline-gentian-violet, Stirling's solution of gentian-vio- 
let, simple aqueous solutions of gentian- or methyl-violet, 
and Ziehl's carbol-fuchsin. 

Gonococcus. — Loffler's solution gives good results. 

Touton recommends staining sections in carbol-fuchsin 
and washing out in alcohol. 

Typhoid Bacillus. — Typhoid bacilli in stained sections 
are generally best hunted for with a low power. The char- 
acteristic colonies which they form are easily recognized. 
Good results in staining can be obtained with Loffler's 
methylene-blue solution used in the manner already de- 
scribed, but the stain is never very intense. For rendering 
the bacilli rather more prominent, so that small groups of 
them may be recognized, Flexner has recently advised the 
two following methods : 

A. — i. Stain paraffin sections in Loffler's methylene-blue 
solution for two hours. 

2. Acetic-acid solution, I : iooo, for several minutes. 

3. Dehydrate in absolute alcohol. 

4. Oil of cloves to clear and differentiate. 

5. Xylol, several changes. 

6. Xylol balsam. 

B. — 1. Stain sections in Stirling's gentian-violet solution 
for ten minutes. 

2. Acetic-acid solution, 1 : 1000, for some minutes. 

3. Dehydrate quickly in 95 per cent, alcohol. 

4. Transfer to slide, blot, add oil of cloves to clear, and 
differentiate. Change the oil several times until the desired 
differentiation is obtained. 

5. Wash off section several times with xylol. 

6. Xylol balsam. 

Influenza Bacillus. — 1. Harden in alcohol. 

2. Stain half an hour or more in carbol-fuchsin diluted 
with 20 parts of water. 

3. Wash out in a watch-glass of water to which is added 



HISTOLOGICAL METHODS. 409 

a drop of glacial acetic acid until the section appears gray- 
violet in color. 

4. Alcohol, xylol, balsam. 

Glanders Bacillus. — The bacilli are usually not numer- 
ous, and are scattered about in a mass of deeply staining 
fragmented nuclei, so that they are recognized with great 
difficulty. 

Loffler's Methylene -blue Stain for Sections. — 1. Stain 
paraffin sections twenty minutes in Loffler's methylene-blue 
solution or in equal parts of aniline-gentian-violet and 
1 : 10,000 KOH solution. 

2. Place for five seconds in the following solution : 

Distilled water, 10 c.c. ; 

Concentrated sulphuric acid, 2 drops ; 

5 per cent, oxalic acid, I drop. 

3. Wash out quickly in distilled water. 

4. Absolute alcohol. 

5. Xylol. 

6. Xylol balsam. 

It is recommended to place the section for a few minutes 
before staining in the 1 : 10,000 caustic-potash solution. 

Schutz's Method. — 1. Stain twenty-four hours in equal 
parts of concentrated alcoholic solution of methylene-blue 
and caustic potash, 1 : 10,000. 

2. Wash in acidified water. 

3. 50 per cent, alcohol for five minutes. 

4. Absolute alcohol for five minutes. 

5. Xylol. 

6. Canada balsam. 

Noniewicz's Method. — 1. Stain in Loffler's methylene- 
blue solution two to five minutes. 

2. Wash in water. 

3. Decolorize one to five seconds in 

\ per cent, acetic acid, 75 parts ; 

\ per cent, aqueous solution of tropeolin, 25 " 

4. Wash in water. 



4IO PATHOLOGICAL TECHNIQUE. 

5. Dehydrate section on slide with filter-paper; then in 
the air ; finally, over small flame. 

6. Clear by dropping xylol on it repeatedly. 

7. Xylol balsam. 

Chancroid Bacillus. — The methods given for the 
glanders bacillus are also useful for this bacillus. 

Friedlander's Capsule -bacillus. — The following 
method is recommended for staining the capsules in sec- 
tions : 

1. Stain for twenty-four hours in the incubator in the fol- 
lowing solution : 

Concentrated alcoholic solution of gentian-violet, 50; 
Distilled water, 100; 

Glacial acetic acid, 10. 

2. Wash out in a 1 per cent, solution of acetic acid. 

3. Alcohol. 

4. Oil. 

5. Canada balsam. 

If the process of decolorization is stopped at the right 
moment, the capsules will be pale blue, while the bacilli 
will be stained deep blue. 

Pathogenic Bacteria which Stain by Gram. 
(See page 95.) 

These organisms, with the exception of the tubercle- 
bacillus group, are all readily stained by the general methods 
employed for staining under Group 1. For staining most 
of them in sections, however, the differential Gram-Weigert 
method will be found to give the most satisfactory results. 

The Gram Staining" Method. — Directions for staining 
paraffin sections : 1 . Stain in aniline-gentian-violet five to 
twenty minutes. 

2. Wash in normal salt solution or water. 

3. Iodin solution (1:2: 300) one minute. 

4. Wash in water. 

5. Absolute alcohol, several changes, until no more color 
is given off and the section is apparently decolorized. 



HISTOLOGICAL METHODS. 41 1 

6. Xylol. 

7. Xylol balsam. 

This method is not suited for celloidin sections, because 
the alcohol does not decolorize the celloidin sufficiently. In 
fact, it is better to reserve Gram's method for cover-slip 
work alone, and to use instead of it, for sections of all kinds, 
Weigert's modification. This consists simply in the use of 
aniline oil instead of alcohol as a decolorizer. The method 
is easily acquired, is perfectly adapted to celloidin sections, 
and the results are more perfect than after Gram. 

The Gram-Weigert Staining 1 Method. — Directions for 
staining celloidin sections: 1. Stain sections with lithium 
carmine in the ordinary way (see page 3 1 3). 

2. After dehydrating in 95 per cent, alcohol stick the sec- 
tion to the slide with ether-vapor. 

3. Stain in aniline-gentian-violet five to twenty minutes. 

4. Wash off excess of stain in normal salt solution. 

5. Iodin solution (1:2: 100) one minute. 

6. Wash off in water. 

7. Blot section with filter-paper to remove as much of the 
moisture as possible. 

8. Aniline oil, several changes, to dehydrate and to re- 
move all excess of color. 

9. Xylol, several changes to remove the aniline oil com- 
pletely. 

10. Xylol balsam. 

Bacillus of Rhinoscleroma.— Method of staining cap- 
sules in sections of tissues hardened in alcohol (Wolko- 
witsch) : 1. Stain twenty-four to forty-eight hours in aniline- 
gentian-violet. 

2. Wash off in water. 

3. Iodin solution one to four minutes. 

4. Absolute alcohol. 

5. Oil of cloves, which removes still more of the color. 

6. Xylol. 

7. Canada balsam. 

According to Wolkowitsch, the hyaline masses in rhino- 
scleroma stain intensely with methyl-violet, gentian-violet, 



412 PATHOLOGICAL TECHNIQUE. 

methylene-blue, and fuchsin ; less with safranin, and not at 
all with hematoxylin. Eosin stains them well. Double 
staining with hematoxylin and eosin is therefore to be 
recommended highly. 

Actinomyces. — In staining the actinomyces it is im- 
portant to stain not only the filaments and other forms of 
the organism, but also the hyaline swollen sheaths which 
surround the ends of the filaments. Eosin followed by 
methylene-blue sometimes gives good results. Good prepa- 
rations can also be obtained by staining in alum-hematox- 
ylin, followed by a strong solution of eosin ; place the sec- 
tions for five to thirty seconds in acid alcohol, and then 
wash thoroughly in water before dehydrating in alcohol. 
It is believed that the two following methods will give better 
results than can be obtained by any of the methods pre- 
viously published for this purpose. The first is, perhaps, 
the better and surer, although the clubs are sometimes 
brought out more intensely by the second method. 

Formaldehyde and alcohol fixation are preferable to 
Zenker's fluid for the study of this micro-organism, but not 
for the study of the lesions produced by it. 

Mallory's Stains. — Method No. 1. — I. Stain sections 
deeply in a saturated aqueous solution of eosin for at least 
ten minutes. 

2. Wash off in water. 

3. Stain in aniline-gentian-violet two to five minutes. 

4. Wash off with normal salt solution. 

5. Iodin solution (1:2: 100) one minute. 

6. Water. Blot with filter-paper. 

7. Aniline oil until section is clear. 

8. Xylol, several changes. 

9. Xylol balsam. 

A light preliminary stain with alum-cochineal will often be 
found useful. 

Method No. 2. — 1. Stain lightly in alum-cochineal three 
to five minutes. 

2. Wash in water. 

3. Dehydrate in 95 per cent, alcohol. 



HISTOLOGICAL METHODS. 413 

4. Fasten section to slide with ether-vapor. 

5. Aniline-gentian-violet five to twenty minutes. 

6. Wash off with water. 

7. Dry with filter-paper. 

8. Aniline saturated with fuchsin one to three minutes. 

9. Wash out the fuchsin with pure aniline until the clubs 
are sharply differentiated : watch the process under the low 
power of the microscope. 

10. Xylol, several changes. 

11. Xylol balsam. 

The polymorphous bacterium is stained blue, the swollen 
membrane (the club), light to dark pink. Alum-cochineal 
furnishes a better contrast to the actinomyces than either 
alum-carmine or alum-hematoxylin. By these methods it is 
possible to demonstrate in sections containing young colonies 
the ends of the threads stained blue surrounded by the 
swollen cell-membrane stained pink. 

Bacteria that Stain by the Tubercle Bacillus Method. 

Tubercle bacillus ; 

Leprosy bacillus ; 

Smegma bacillus ; 

Syphilis bacillus. 
The important point about staining tubercle bacilli is to 
stain them deeply enough in the beginning ; then there is 
little danger of their fading in the subsequent steps of con- 
trast staining. It is probable that carbol-fuchsin, used hot, 
is the most powerful stain we have for this purpose. If the 
solution is steamed, generally on the slide, one to five min- 
utes are probably sufficient for all purposes. Tubercle bacilli 
stain well, not only after alcohol, but also after most of the 
other fixing reagents, such as corrosive sublimate, Zenker's 
fluid, Flemming's solution, etc. 

Ehrlich's Method. — 1. Stain paraffin sections in aniline- 
fuchsin or gentian-violet for half an hour to twenty-four 
hours, or for one to five minutes if solution is heated to 
steaming. 

2. Wash in water. 



414 PATHOLOGICAL TECHNIQUE. 

3. Decolorize in 20 per cent, nitric acid one-half to one 
minute. 

4. Wash in 70 per cent, alcohol until no more color is 
given off. 

5. Contrast-stain in a saturated aqueous solution of methy- 
lene-blue or of Bismarck brown one to two minutes. 

6. Wash in water. 

7. Dehydrate in absolute alcohol. 

8. Xylol, xylol balsam. 

Ziehl-Neelson-Gabbet Method. — 1. Stain paraffin sec- 
tions in carbol-fuchsin solution, warming the solution so that 
it steams one to three minutes. 

2. Wash in water. 

3. Decolorize and stain for contrast in sulphuric-acid- 
methylene-blue solution one minute (see page 288). 

4. Wash in water. 

5. Absolute alcohol. 

6. Xylol. 

7. Xylol balsam. 

This method is not suited to celloidin sections, because 
the celloidin retains too deep a blue stain. 

Ktihne's Method. — 1. Stain paraffin sections lightly in 
alum-hematoxylin. 

2. Wash in water. 

3. Stain in carbol-fuchsin one to five minutes if warmed ; 
longer if cold. 

4. Wash in water. 

5. Aniline hydrochlorate, 2 per cent, aqueous solution, 
fifteen seconds. 

6. Wash in water. 

7. Absolute alcohol. 

8. Xylol. 

9. Xylol balsam. 

To Stain Tubercle Bacilli in Celloidin Sections. — 1. 
Stain rather lightly in alum-hematoxylin. 

2. Wash in water. 

3. Dehydrate in 95 per cent, alcohol. 

4. Attach sections to slide by the ether- vapor method. 



HISTOLOGICAL METHODS. 415 

5. Carbol-fuchsin two to five minutes steaming. 

6. Water. 

7. Orth's discharging fluid (acid alcohol) one-half to one 
minute. 

8. Wash thoroughly in several changes of water to re- 
move acid completely and to bring back blue color to nuclei. 

9. Alcohol 95 per cent, until fuchsin is entirely discharged. 

10. Aniline followed by xylol; or blot and treat with 
xylol. 

1 1. Xylol balsam. 

The advantages of this method are — that the celloidin is 
colorless ; the nuclei are stained blue ; the rest of the tissue 
is colorless; the tubercle bacilli stand out in sharp contrast. 
It is sometimes an advantage to bring out the cell-proto- 
plasm and the intercellular substance by staining the sec- 
tions, after decolorization in alcohol, in an aqueous solution 
of orange G or methyl-orange for a few seconds. 

The bacillus of leprosy stains more easily than the 
tubercle bacillus. Simple aqueous solutions of the aniline 
dyes are sufficient. The same methods can be employed as 
for tubercle bacilli. A method recommended by Flexner 
will be found very useful. 

1. Stain in alum-hematoxylin so as to get a sharp nuclear 
stain. 

2. Wash in water. 

3. Carbol-fuchsin two to five minutes steaming, or thirty 
to sixty minutes cold. 

4. Water. 

5. Treat on the slide with iodin solution one-half to one 
minute. 

6. Water. 

7. Blot ; clear and differentiate in aniline oil. 

8. Xylol ; balsam. 

Baumgarten gives the following differential stain for 
leprosy bacilli : 

I. Stain six to seven minutes in a dilute solution of fuch- 
sin (5 drops of a concentrated alcoholic solution to a watch- 
glass of water). 



416 PATHOLOGICAL TECHNIQUE. 

2. Discharge one-quarter minute in nitric-acid alcohol 
(nitric acid I, alcohol 10). 

3. Wash in water. 

4. Contrast-stain in a saturated aqueous solution of meth- 
ylene-blue. 

5. Alcohol. 

6. Xylol. 

7. Balsam. 

While leprosy bacilli stain readily by this method, tubercle 
bacilli will not stain in so short a time. 

Syphilis Bacillus. — Lustg-arten's Method. — 1. Stain 
twenty-four hours at room-temperature and two hours in 
the thermostat at 40 in aniline-gentian-violet. 

2. Wash off in absolute alcohol three to five minutes. 

3. Decolorize {a) in a \ per cent, aqueous solution of per- 
manganate of potassium, and then (/;) a few seconds in an 
aqueous solution of pure sulphurous acid (strength not 
given). 

4. Wash in water. 

5. Alcohol. 

6. Oil of cloves. 

7. Canada balsam. 

If the section is not entirely decolorized when the section 
is put into water, then the third step must be repeated until 
decolorization is complete. If desired, the sections can be 
stained in safranin after the fourth step. 

Giacomi's Method. — 1. Stain several minutes in hot ani- 
line-fuchsin. 

2. Wash out in very dilute aqueous solution of chlorid of 
iron. 

3. Decolorize in concentrated solution of chlorid of iron. 

4. Wash out in absolute alcohol. 

5. Xylol. 

6. Xylol-balsam. 

The smegma bacillus is stained by Lustgarten's method, 
but not by the methods given for tubercle bacilli in tissues, 
because in all of them alcohol is used as well as an acid to 
effect the decolorization. 



HISTOLOGICAL METHODS. \\J 

METHODS OF EXAMINATION OF ANIMAL PARASITES. 

Malarial Organisms. — Three varieties of the plasmodium 
malariae have been described — namely, the tertian, quartan, 
and estivo-autumnal parasites. They develop within the red 
corpuscles and cause the destruction of the corpuscles 
affected. The earliest forms of the parasite appear in the 
blood during the latter part of the malarial paroxysm or 
shortly after it. At this time they appear as small, color- 
less, disc-shaped hyaline bodies which occupy but a small 
portion of the blood-corpuscles. They possess a varying 
degree of ameboid movement, the amount depending upon 
the type of the organism. These ameboid movements are 
best observed on the warm stage. During the process of 
development the parasites increase in size and more or less 
completely fill the red corpuscles containing them. Small 
particles of reddish-brown pigment are produced, during 
their growth, from the hemoglobin of the corpuscles in 
which the organisms are developing. These granules show 
varying degrees of motion, probably imparted to them by 
the movements of the parasites. At first the pigment ap- 
pears to be scattered about in the corpuscle, but it is in real- 
ity in the extremities of the pseudopodia. Later it appears 
more evenly spread about in the periphery. Toward the 
end of the cycle of development the pigment collects in the 
center of the parasite ; at this time the ameboid movements 
have ceased, indications of segmentation occur, and the 
parasite nearly or completely fills the corpuscle. Oftentimes 
at this stage only a small portion of the corpuscle is visible 
at some point on the edge of the parasite.. 

The beginning of segmentation is indicated by a number 
of radial lines extending from the periphery of the parasite 
toward the central clump of pigment. Segmentation takes 
place, and the pigment is surrounded by a number of dis- 
tinct segments which vary with the type of the organism. 
Each of these segments shows a central refractive spot 
which probably is the nucleus. At this time one notices 
small hyaline bodies, like those of the early stage in the de- 
velopment of the parasite, in some of the red blood-cor- 

27 



41 8 PATHOLOGICAL TECHNIQUE. 

puscles. Oftentimes such a regular process of segmentation 
is not observed, but enough has been said to indicate the 
manner in which reproduction occurs. Segmentation is the 
indication of an approach of a paroxysm. Extra-cellular 
forms of the parasites are not infrequently seen. They may 
be fully grown organisms which have destroyed the cor- 
puscles that contained them, or they may be partly grown 
organisms which have left the corpuscles. These free para- 
sites are indistinct in outline and contain pigment. They 
possess ameboid movements, and may be considerably larger 
than a red blood-corpuscle. Various changes are observed 
in them : 

1. They may increase in size until they become nearly as 
large as polymorphonuclear leucocytes. With the increase 
in size there is a gradual cessation in the movement of the 
pigment-granules, until finally the organisms present the ap- 
pearance of misshapen masses of protoplasm containing 
motionless pigment-granules. 

2. They may undergo fragmentation and give off several 
small circular pigmented bodies. 

3. Vacuolization may occur. 

4. Flagellate forms may develop. One or more thread- 
like processes are thrust out from the organisms. These 
flagella may contain pigment, and may break away from the 
organism and move about among the corpuscles, looking not 
unlike the spirilla of relapsing fever. 

The three varieties of parasites differ from one another in 
a number of ways. The chief differences are the length of 
the cycle of development ; the size of the full-grown organ- 
isms ; the difference in the refractibility of the organisms ; 
the quantity, size, and color of the pigment-granules ; the 
degree of ameboid movement ; and the number and shape 
of the segments into which the full-grown organisms divide. 
In the earliest stage the varieties or organisms cannot be dis- 
tinguished from each other. 

The tertian parasite completes its cycle of development in 
about forty-eight hours. When it has attained its fullest 
growth it almost fills the corpuscle, which has become 



/ 


2 






3 








t mm. M |-JBBH| 


5 



Tertian malarial parasites in red blood-corpuscles (Wright's stain) : i, Young 
parasites (in the corpuscle on the right two or three parasites) ; 2, young parasites ; 
3, half-grown parasites; 4, half-grown parasite (on the left, a blood-plate and near 
the center another blood-plate lying on a red corpuscle) ; 5, half-grown parasites 
(in the corpuscle on the left two parasites) ; 6, full-grown parasite (the nucleus lies 
in a clear space). All the infected blood-corpuscles in the foregoing figures contain 
minute granules that stain red (granular degeneration) (photos by L. S. Brown). 




Two stages in the process of segmentation of a tertian malarial parasite in 
a red blood-corpuscle. Preparation of fresh blood, not stained (Wright and 
Brown). 





*v* 




HHBHH 







Tertian malarial parasites in red blood corpuscles (Wright's stain) : i, Young 
parasite ; 2, young parasite with blood plate at the margin of the corpuscle; 3, 
two young parasites in one corpuscle ; 4 and 5, immature parasites ; 6, immature 
parasite (on the left two blood plates) ; 7, adult parasite (chromatin of nucleus 
in clear space) ; 8 and 9, adult parasites (the chromatin is the reticular mass 
near the center of the parasites) ; io, segmenting parasite (the chromatin has 
divided into a number of separate dark colored masses. In the center some 
pigment). In all of the foregoing figures, except Figure i, the granular degen- 
eration of the infected red corpuscles is shown (photos by L. S. Brown). 



HIS TO L O GICAL ME THODS. 



419 



larger than normal. This organism is less refractive than 
either of the other two. The pigment-granules are more 
numerous, finer, and more reddish-brown in color; the ame- 
boid movements are much more active ; the segments are 
more irregular in shape and more numerous than those of the 
quartan parasite, varying from twelve to twenty in number. 










\ 








Fig. 119. — Estivo-autumnal malarial parasites in red blood-corpuscles 
(1, 2, 3, and 4, Wright's stain): 1, 2, and 4, young parasites; 3, on the left, a 
" crescent," on the concave side of which is shown a portion of the periphery 
of the red corpuscle, which it distends; on the right, a young parasite ; 5 and 7 
"crescents" in red blood-corpuscles; 6, ovoid form of parasite in a red blood- 
corpuscle (photos by L. S. Brown). 

The quartan appears to complete its cycle of development 
in from sixty-four to seventy-two hours. The full-grown 
organism does not fill completely the corpuscle, and the latter 
is not increased in size. The organism is more refractive 
than the tertian parasite. The pigment-granules are fewer 



420 PATHOLOGICAL TECHNIQUE. 

in number, coarser, and have a darker-red color. The ame- 
boid movements are slower ; the segments are pear-shaped, 
more symmetrical, and less numerous than those of the ter- 
tian parasite, varying from six to twelve in number. Seg- 
menting organisms are more numerous in the peripheral 
circulation than in the case of the tertian parasite. 

The estivo-autumnal parasite cannot be studied so thor- 
oughly in the peripheral circulation, because the later develop- 
ment and segmentation take place in the internal organs. The 
length of time required to complete its cycle of development 
is not so definitely settled. It appears to require from twelve 
to twenty-four hours, more or less. The full-grown organ- 
ism is smaller than the tertian parasite, and the corpuscle 
which contains it is often smaller than normal and more or 
less distorted. The parasite is quite refractive. The pig- 
ment-granules are few in number and coarse. The ameboid 
movements are slow. After the duration of fever for from 
five days to a week or more, elongated, ovoid, or crescent- 
shaped bodies make their appearance. They are sometimes 
as large or larger than a red corpuscle. These bodies are 
not a result of segmentation, but appear to be a further de- 
velopment of the round hyaline bodies. They are highly 
refractive and contain granules of coarse pigment in the 
center. They lie usually at one side of the red corpuscles, 
the latter more or less completely filling the concavity be- 
tween the two horns of the crescent. They may lie in the 
center of the corpuscles. Some of the apparently free ovoid 
bodies are turned in such a way as to present a convex sur- 
face toward the observer. 

Double infections occur quite frequently in both tertian 
and quartan fever, and in the latter not infrequently triple 
infections occur. In the double infections two groups of 
parasites reach maturity on successive days and cause daily 
febrile paroxysms. In the triple infection of quartan fever 
three groups of organisms mature on successive days and 
cause corresponding paroxysms. 

Note. — The description of the development of the parasites is abstracted 
from Thayer and Hewetson' s The Malarial Fevers of Baltimore. 



HISTOLOGICAL METHODS. 42 1 

Methods of Examining the Blood for Malarial Organisms. 
■ — The organisms of malaria can be detected in fresh speci- 
mens of blood or in specimens of blood which have been 
fixed and stained. 

In doubtful cases the parasites are more surely and easily 
found in cover-glass preparations of the blood fixed and 
stained by special methods. 

The method employed in making cover-glass preparations 
of the blood has been thoroughly described (see preparation 
of cover-glass specimens in the Examination of the Blood, 
page 368). 

Wright's stain for malarial parasites is identical with his 
blood-stain and is applied in the same way (see page 370). 
It gives the so-called Romanowsky stain to the parasites. 

With the stain, the body of a malarial parasite stains blue, 
while the color of the chromatin varies from a lilac color 
through varying shades of red to almost black. In the 
young forms of the tertian and estivo-autumnal parasites the 
chromatin appears as a spherical, very dark-red body, while 
in the older forms of the tertian parasite it has a more lilac 
or purplish-red color, and may appear in the form of a 
reticulum. In the intermediate forms the color of the chro- 
matin may present variations between these extremes (see 
Fig. 119). 

Blood plates apparently situated within red blood-cor- 
puscles may be mistaken by the inexperienced for young 
malarial parasites. This ought never to occur if one bears 
in mind the fact that the young parasite of all the three 
kinds should present by this method a dark-red, spherical 
nucleus and a homogeneous blue cytoplasm which is usually 
in the form of a definite ring (see Fig. 1 19). 

Various workers have shown by their modifications of the 
Romanowsky method that red blood-corpuscles harboring 
malarial parasites have dark-red staining granules. These 
granules may be brought out by the present method, but in 
order to bring them out, it may be necessary to allow the 
staining fluid, after the addition of the water to it, to remain 
on the preparation for at least five minutes, and then not to 



422 PATHOLOGICAL TECHNIQUE. 

decolorize or differentiate with water for as long a time or to 
such an extent as for ordinary blood preparations. 

In examining a fresh specimen of the blood for the malarial 
organisms a glass slide is substituted for one of the cover- 
glasses, and the cover-glass which has the drop of blood on 
its surface is dropped lightly upon the glass slide and allowed 
to remain there. The first four or five drops of blood 
should be quickly wiped away from the ear until a very 
small drop is obtained. Great care must be exercised to 
touch only the tip of the drop with the cover-glass, so as to 
avoid smearing the blood. If the blood is smeared on the 
cover-glass, the edges of the blood-drop will dry before the 
cover-glass can be transferred to the slide, and the blood will 
not spread. It is necessary that the blood should spread in 
a thin layer in order to study satisfactorily the individual 
corpuscles. If one desires to study the preparation for 
several hours, the edges of the cover-glass can be sur- 
rounded by melted paraffin or vaselin to exclude the air. 
The examination should be made with an oil-immersion lens. 
It should be remembered that the action of cold inhibits the 
ameboid movements of the parasites ; it may be necessary, 
therefore, at times to warm the slide before examining the 
specimen. Evaporation not infrequently occurs, caused by 
the air penetrating beneath the cover-glass. This produces 
changes in many of the corpuscles which may be mistaken 
for hyaline bodies : the central depression becomes paler and 
less refractive than the periphery of the corpuscles ; later a 
number of corpuscles contain small glistening points, and 
still later the corpuscles become crenated. 

Amoeba Coli. — In cases of dysentery suspected of being 
due to the amoeba coli (Fig. 120) the stools are best examined 
as soon as voided, although the amebae will sometimes re- 
main active in stools even over twenty-four hours old. A 
warm stage during the examination is an advantage, but not 
a necessity. A drop of the fluid material, preferably that 
containing mucus or blood, is placed on a slide and lightly 
covered with a cover-glass. If the slide is cold and the or- 
ganisms do not move, warm the slide gently and the move- 



HIS TO 10 GICA L ME THODS. 



42 3 



ments of the amebae will often start up. Pus from abscesses 
due to the amebae is examined in the same way. A positive 
diagnosis rests on the presence of the characteristic large, 
pale cells, consisting of nucleus, granular endosarc, and 
hyaline ectosarc, and on the movements of the protoplasm, 
which projects itself more or less actively in the form of 
pseudopodia. 

In hardened preparations the nuclei of the amebae do not 
stain with the ordinary nuclear stains, such as alum-hema- 
toxylin and methylene-blue. The following method of 
staining them has been found to give very satisfactory 







Fig. 120. — Amoebae coli in intestinal mucus (after Losch). 

results and to render the recognition of the organisms 
easy: 

Differential Stain for the Amoeba Coli (Mallory). — 1. 
Harden in alcohol. 

2. Stain sections in a saturated aqueous solution of thionin 
three to five minutes. 

3. Differentiate in a 2 per cent, aqueous solution of oxalic 
acid for one-half to one minute. 

4. Wash in water. 

5. Dehydrate in absolute alcohol. 

6. Clear in xylol. 

7. Xylol-balsam. 

The nuclei of the amebae and the granules of the mast- 



424 



PA THOL O GICA L TE CHNIQ UE. 



zellen are stained brownish red ; the nuclei of the mastzellen 
and of all other cells are stained blue. 

Excellent results were obtained by this method with bits 
of the purulent discharge from a so-called amebic abscess 
of the liver. After hardening in 95 per cent, alcohol, small 
fragments the size of a pin-head and less were stained as 
above directed, and teased apart after they were in the 
balsam. The reddish nuclei stood out so sharply in the 




Fig. 121. — Adult male filaria Bancrofti ; X 10 (after Lothrop and Pratt). 



bluish background of fragmented nuclei and granular de- 
tritus that they were easily picked out with the high dry 
power. 

The results obtained with feces examined in the same way 
or after imbedding in celloidin were much less .satisfactory, 
for the reason that various substances in the feces precipitate 
the thionin in the form of reddish crystals and give rise to 
deceptive pictures. A similar differential stain can be ob- 
tained by Unna's method for staining the granules of mast- 
zellen (see page 321). 



HISTOLOGICAL METHODS. 



425 



Other protozoa, such as the cercomonas and trichomonas, 
are best examined in fresh preparations. 

Sporo^oa. — The coccidium oviforme should be examined 
both fresh in cover-slip preparations and in sections after 
hardening. The cyst-forms often stain well by the tuber- 
cle-bacillus method. For studying all the stages in the 
development of the organism, Pianese recommends highly 
his special fixing reagent and stains (see p. 293). Other 
sporozoa should be studied in the same manner, or by the 
eosin-methylene-blue stain after fixation in Zenker's fluid. 
Cover-slip preparations are often useful. 



t 



a b 

Fig. 122. — Photomicrographs of living filarial sanguinis hominis ; X 250, a, from 

hydrocele fluid; b, from blood (after Lothrop and Pratt). 



Round-worms. — The embryos of the filaria satiguinis 
hominis or filaria Bancrofti (Fig. 121) are examined for in 
suspected cases by mounting a drop of the fresh blood or 
of the chylous or bloody urine on the slide and examining 
under a low power. They are readily detected when present 
on account of their very active movements. Six species 
have been described, but the filaria nocturna is the only 
one that is known to be pathogenic. The blood should 
be examined during the resting hours of the patient, as 
at night for day-workers and during the day for night- 
workers. Permanent specimens can be made by fixing 
ordinary cover-slip preparations of the blood or chylous 
fluid by heat or by the use of a saturated solution of cor- 
rosive sublimate, and staining for a few seconds with 
Loffler's methylene-blue or with a 2 per cent, aqueous 
solution of thionin. 



426 



PA THOL O GICAL TE CHNIQ UE. 



Trichinae (Figs. 123, 124) are obtained from the fresh 
muscle by means of teasing. A quick method is to squeeze 
small bits of tissue between two slides and examine with a 





FIG. 123. — Living embryos 
(Heller). 



Fig. 124. — Encapsulated trichina 
(Leuckart). 



low power. Pieces of muscle nearest the insertion of the 
tendon are chosen from the diaphragm or from the muscles 
of the jaws. Encapsulated and calcified trichinae are cleared 
up by means of acids. 






Fig. 125. — Taenia solium : A, head enlarged; B, ripe joint, X 6 ; C, egg of 
taenia solium (Heller). 



In hardened tissues the trichinae are best studied in longi- 
tudinal sections of the muscle-fibers. 

The other round-worms which sometimes occur in the 



HIS TO I O QIC A I ME THODS. 



427 

Their 



intestinal tract can be recognized with the naked eye 
eggs must be looked for with the microscope. 

Tape-worms. — It is not always easy to recognize the 
kind of tape-worm by a single segment passed with the feces, 



-■^N 






A B C 

Fig. 126. — Taenia mediocanellata : A, head darkly pigmented ; B, ripe joint, 
X 6 ; C, egg of taenia mediocanellata. 

because the uterus, which furnishes the most characteristic 
points of difference, is not developed in the young segments 
and is atrophied in the old ones. When the whole worm is 
obtained the problem is much simpler. The uterus is best 




f 







Fig. 127. — Echinococcus : scolices, hooks (Heller). 

made out by squeezing a segment between two slides and 
holding it up to the light. The heads are examined under 
the microscope in water, salt solution, or glycerin. 

Taenia Solium (Fig. 125). — Head has four suckers and a 
circle of hooklets ; uterus is noticeably but little branched. 



428 



PA THOL O GICA L TE CHNIQ UE. 



The genital tract opens laterally. The eggs develop into the 
cysticerci cellulosae, which are not infrequently found in man. 
The scolex is obtained for examination by tearing open the 




A 
FIG. 128.— Bothriocephalus latus : A, head; B, ripe joint, X 6; C, egg of bothrio- 
cephalus latus (Heller); D, egg with developed embryo (Leuckart). 

cyst and examining the inner wall. The suckers and hook- 
lets are best studied after mounting fresh and pressing under 
a cover-glass. 




FIG. 129. — Segments of taenia 
saginata (after Stein). 



FlG. 130. — Segments FlG. 131. — Segments 
of bothriocephalus latus of taenia solium (after 
(after Stein). Stein). 



Taenia Medio canellata s. Saginata (Fig. 126). — Head 
has four strong suckers, but no hooklets ; uterus is very 



HISTOLOGICAL METHODS. 



429 



much branched, segments show marked muscular develop- 
ment. The genital tract opens laterally. The eggs develop 
into cysticerci, which do not occur in man. 

Tsenia Echinococcus (Fig. 127) occurs in dogs. The 
echinococcus cysts which occur in man are recognized by 
the very characteristic laminated structure of the cyst-wall. 
The heads of the scolices have four suckers and a double 
circle of hooklets. 





Fig. 132. — Comparative size of eggs of intestinal parasites : a, taenia solium ; 
b, taenia mediocanellata ; c, ascaris lumbricoides ; d, trichocephalus dispar; e, 
oxyuris vermicularis (after Striimpell). 

Bothriocephalus Latus (Fig. 128). — The opening of the 
genital tract lies in the median line. The head is flattened, 
and has two small suckers situated at the sides. 



CLINICAL PATHOLOGY. 

The material received at the pathological laboratory from 
clinical cases consists largely of new growths and lesions 
produced by infectious, chemical, or traumatic agents — to a 
less extent of fluids from various natural or artificial cavities 
or secretions and eliminations from the respiratory, genito- 
urinary, and gastro-intestinal tracts. In the following pages 
a brief synopsis is given of what may be expected in the 
various fluids and eliminations, and the more important 
chemical tests required for the recognition of certain sub- 
stances are added. 

Gross specimens removed at operations should be treated 
as parts of autopsies, and dissected or otherwise examined 
bacteriologically and histologically in an equally careful 



43° PATHOLOGICAL TECHNIQUE. 

manner. For the finer study of cancers and other new 
growths the recently published methods of Pianese should 
be employed (see page 293). 

Examination of Tissues from Clinical Cases for 
Diagnosis. — Tumors of any size or large pieces of tissue 
present no difficulties. There is plenty of material to ex- 
amine fresh or after fixing in a variety of ways. The small 
bits removed with a Mixter punch or cut from the edge of a 
growth, of which a diagnosis is wanted immediately, some- 
times prove troublesome. Frozen sections of the fresh 
tissue are often sufficient. Sometimes it is better to harden 
for an hour or more in formaldehyde and then to make 
frozen sections. 1 Often it is wisest to harden in strong alco- 
hol and then to make razor sections or to imbed in celloidin. 
The whole process of hardening, imbedding, and sectioning 
can easily be carried through in twenty-four hours with 
small pieces of tissue. Imbedding in paraffin is sometimes 
preferred. In cutting sections of small pieces it is important 
to mount them if possible, so that the cut sections will show- 
proper relations — i. c, vertical sections through the skin, 
uterine mucous membrane, etc. — otherwise confusing pict- 
ures will often be presented. It is important to know, in 
regard to pieces of tissue sent for diagnosis, from what part 
of the body they come. 

A hematoxylin-and-eosin stain will be found the most 
generally useful for hardened sections. 

Uterine Scrapings. — Small pieces may be examined 
fresh in frozen sections or after hardening for one or more 
hours in formaldehyde. Better results are obtained by hard- 
ening in alcohol and imbedding in celloidin or paraffin. 
Where the fragments are small, it is advisable to mass them 
together on a small piece of filter-paper and to harden in 
strong alcohol. The mass can then be imbedded in celloidin 
and cut as one piece of tissue, or they can be carried through 
by the gelatin-formaldehyde imbedding method (see p. 279), 
and cut on the freezing microtome. A hematoxylin-and- 
eosin stain is the best, because the eosin brings out the 
1 For frozen section methods, see p. 240. 



HISTOLOGICAL METHODS. 43 I 

smooth muscle-fibers prominently, so that any invasion of 
the muscular coat by a malignant growth is more readily 
made out — a valuable help in the diagnosis of malignant 
adenoma. 

Examination of Fluids obtained by Puncture. — 
The transudations obtained largely from the serous cavities 
are non-inflammatory in origin. They are usually of a trans- 
parent, pale-yellow color with slightly greenish tint, alka- 
line in reaction, and deposit on standing a slight flocculent 
coagulum. 

The specific gravity, to be taken at room-temperature, 
varies according to the origin of the fluid. According to 
Reuss, it is below 1015 in hydrothorax ; below 10 12 in 
ascites; below 1010 in anasarca; below 1008.5 m hydro- 
thorax. 

The amount of albumin in hydrothorax is always under 
2.5 per cent., and in ascites between 1.5 and 2 per cent. 
Microscopically, a few leucocytes, usually fatty degenerated 
and rarely desquamated endothelial cells, are found. 

The exudations are of inflammatory origin, and are also 
generally obtained from the serous cavities. From their 
various microscopic appearances they are divided into serous 
(fibrino-serous), hemorrhagic, purulent, and gangrenous. 
The specific gravity of all is over 1018 ; the reaction is always 
alkaline. On standing they deposit a varying amount of 
sediment. Examinations for organisms should always be 
made. Occasionally a peculiar opalescent layer, due to 
cholesterin crystals, forms on the surface of fluids which 
come from old cases of pleurisy. 

Serous Exudations. — The fluid, which immediately after 
removal is slightly cloudy and yellowish in color, deposits 
more or less quickly a flocculent or dense coagulum. Micro- 
scopically, the coagulum shows a dense meshwork of fibrin 
and numerous polynuclear leucocytes. 

Hemorrhagic Exudations. — The sero-fibrinous exudation 
is colored a lighter or darker red according to the amount 
of blood present. Microscopically, the same elements are 
found as in the serous exudations, plus a marked increase 



432 PATHOLOGICAL TECHNIQUE. 

of red blood-globules, which are usually well preserved, but 
in old exudations may be more or less decolorized. 

Aside from injuries, hemorrhagic exudations are most 
common in connection with tuberculosis and new growths, 
so that their microscopic examination is of much diagnostic 
and prognostic value. 

For the examination for tubercle bacilli see page 184. In 
this form of exudation it is rarely possible to demonstrate 
them. On the other hand, it is not infrequently possible to 
make the diagnosis of a malignant growth, especially of 
cancer, from the examination of the sediment. No cell is 
significant of cancer or other neoplasm, but the occurrence 
of numerous cells which vary greatly in form is suspicious. 
The cells from new growths are often unusually large, up to 
120/i, frequently contain one or more vacuoles, and usually 
lie in clumps. Large drops of fat are also considered sus- 
picious. 

A positive diagnosis can only be made by obtaining bits 
of tissue which show the structure of the new growth, such 
as the atypical alveolar arrangement of the cells in cancer. 

Purulent exudations appear more or less thick and yel- 
low, and deposit a corresponding layer of pus. Microscopic- 
ally, they present no peculiarities other than the organisms 
to which they are due. Among the etiological factors acti- 
nomyces must always be thought of in puzzling cases. 

Putrid exudations occur in the pleural and peritoneal 
cavities in consequence of gangrenous masses breaking into 
them and from stomach or intestinal ulcerations, from new 
growths, occasionally from no clear cause. The fluid result- 
ing from the perforation of a gastric ulcer may show yeast- 
cells and sarcinae, and give an acid reaction. 

Examination of Serous Fluids. 1 — In 1900 Widal and 
Ravaut 2 published a method for the examination of serous 
fluids and gave it the name of cytodiagnosis. Recently 

1 This section has been written by Dr. Percy Musgrave, who has thoroughly 
tested these methods in the Clinico- Pathological Laboratory of the Massachu- 
setts General Hospital. 

2 Compt. rend, de la soc. de biol. de Paris, 1900, p. 648. 



HISTOLOGICAL METHODS. 433 

Jousset 1 has described a method for the detection of the 
bacillus tuberculosis, under the name of inoscopy. These 
two methods have- been found of much importance in the 
examination of serous effusions as means of determining 
their etiology. 

Cytodiagnosis consists in the examination of the cellular 
elements with reference to the variety of cell which predomi- 




FlG. 133. — Cytodiagnosis. Polynuclear leucocytes and swollen endothelial 
cells in a smear preparation from the centrifugalized sediment of the fluid from 
an acute infectious non-tubercular pleuritis (Percy Musgrave ; photo by L. S. 
Brown). 

nates in the sediment. The originators of this method have 
given us the following formulae : 

1. Predominance of polynuclear leucocytes means an acute 
infectious process. 

2. Predominance of lymphocytes means tuberculosis. 

3. Few cellular elements with a large proportion of endo- 
thelial cells, occurring especially in sheets or plaques, means 
a transudate or mechanical effusion. 

These writers have given us no special formula for cancer, 
but there is reason to believe that cancerous fluids show a 
relatively large number of endothelial cells mixed with a 
larger percentage of lymphocytes than is found in the me- 
chanical effusions, and also that cancerous fluids have a large 

1 La Semaine Medicale, January 21, 1903. 
28 



434 



PA THOL O GICA L TE CHNIQ UE. 



amount of albumin and a high specific gravity. Further 
research, however, on this point is necessary. 

The age of the effusion in the acute infectious variety has 
some modifying effects, for which the reader is referred to the 
original articles. 

In the tubercular variety, although there is usually a high 
percentage of lymphocytes in the first ten days, the poly- 
nuclear leucocytes may predominate, but after the second 
week the formula remains fairly constant. 




Fig. 134. — Cytodiagnosis. Lymphoid cells in a smear preparation from the 
centrifugalized sediment of pleural fluid; case of tubercular pleuritis (Percy 
Musgrave ; photo by L. S. Brown). 

The so-called secondary tuberculous pleurisy (caused by 
direct extension from a tuberculous focus in the lung) often 
shows a large number or even a predominance of poly- 
nuclear leucocytes, owing to a 
pyogenic bacteria. 

Old mechanical effusions are 
where little endothelium is seen, 
almost exclusively lymphocytes. 

Method. — The fluid should be drawn with the usual 
aseptic precautions into sterilized flasks or tubes. If it is 
clotted, it should be shaken until the clot is thoroughly con- 



secondary infection with 

occasionally encountered 
. and the cells found are 



HISTOLOGICAL METHODS. 435 

tracted, and the clot, or all clots of large size, should be 
removed. 

Place the fluid in centrifuge tubes and centrifugalize for 
five minutes at least. 

Decant the supernatant fluid gently at first, and when a 
small amount only remains, invert the tube for about two 
seconds. A few drops only will be left. 

With a small platinum loop stir the sediment thoroughly, 
rubbing the sides of the glass to remove adherent portions. 
When the sediment is thoroughly mixed with the few drops 




Fig. 135. — Cytodiagnosis. Endothelial cells in a smear preparation from 
the centrifugalized sediment of a transudate or mechanical effusion (Percy Mus- 
grave ; photo by L. S. Brown). 

of fluid remaining after decantation, remove a drop of the 
mixture with the platinum loop and make a cover-slip smear. 
Allow this to dry spontaneously or by very gently heating. 
Heating at the boiling-point will spoil the preparation. 

Cover the preparation with a staining fluid made as fol- 
lows : 

Wright's blood-stain, 3 parts ; 

Pure methyl-alcohol, I part. 

Allow to remain on the preparation twenty to forty-five 
seconds, then dilute it with 8 to 10 drops of water and allow 
this mixture to stand one to two minutes. 



43 6 PATHOLOGICAL TECHNIQUE. 

Wash very gently, preferably by flooding the slide with a 
dropper. Do this four or five times, allowing the water to 
remain on the slide a few seconds each time. Vigorous or 
forcible washing will destroy the film and spoil the prepara- 
tion. 

Dry the preparation by holding it between the thumb and 
forefinger and waving it through the Bunsen or alcohol 
flame. Do not attempt to blot the preparation or heat it 
above the temperature which the fingers will bear. 

lyiount in xylol-balsam and examine with an oil-immersion 
lens. 

Inoscopy is practised as follows : 

1. The fluid should be drawn with asceptic precautions 
into sterilized flasks (Erlenmeyer flasks preferably), and at 
least ioo c.c. should be taken, although results may some- 
times be obtained with much smaller amounts. Allow the 
fluid thus taken to clot. 

2. Shake the fluid gently to contract the clot as much as 
possible, and then wash it, on a piece of sterile linen or fine 
gauze wrapped over the end of a funnel, until all the serum 
is washed away. 

3. Remove the clot or clots with a sterile spatula and 
place in a small flask with sufficient of the following fluid to 
digest it : 

Pepsin, 2 gm. ; 

Pure glycerin 1 h " 

Strong HC1 J 

Sodium fluoride, 3 gm. ; 

Distilled water, IOOO c.c, 

The amount of this fluid necessary will vary, of course, 
with the size of the clot to be digested, but 20 or 30 c.c is 
sufficient in most cases. A freshly prepared pepsin — HC1 
solution — apparently serves as well as the above fluid. 

4. Place the above preparation in the incubator or oven 
until the clot is digested. A temperature of 37 C. for two 
or three hours will suffice, but the time is shortened if kept 
at a temperature of 50 C. 



HISTOLOGICAL METHODS. 437 

5. When the clot has disappeared, pour the mixture into 
centrifuge tubes and centrifugalize for five to ten minutes. 
Decant the supernatant fluid as described under cytodiag- 
nosis (see p. 434)- 

6. Make a cover-slip preparation and stain it for tubercle 
bacilli. Care, however, should be taken not to decolorize 
too long — one-half to three-quarters of a minute with Gab- 
bet's solution is sufficient. Dry and mount. 

The majority of the bacilli found by this method are 
shorter and broader, as a rule, than the tubercle bacilli 
ordinarily seen in sputum, and some are paler red, but all 
the forms occur. These bacilli may occur singly or in 
groups. The greater part of the sediment consists of undi- 
gested nuclei and a small amount of detritus. 

Animal inoculation gives the most satisfactory results 
if practised as follows : 

Take at least two centrifuge tubesful of the fluid and cen- 
trifugalize for ten minutes. Decant the supernatant fluid 
and add about 10 m. of the original fluid to each tube. 
Stir up the sediments in the two tubes until thoroughly sus- 
pended ; then mix them and inoculate a guinea-pig subcu- 
taneously. Not over 30 m. of fluid should be used, since 
this is sufficient, and in most cases does not cause toxemia 
in the animal. 

Cultures from purely serous fluids are, in the vast majority 
of cases, sterile. In a few cases the writer has found the 
pneumococcus and streptococcus in pure culture. 

lumbar Puncture.— The diagnostic value of lumbar 
puncture has been sufficiently demonstrated. Not only is 
it possible to diagnosticate inflammation of the meninges, 
but the character and cause of the inflammation may usually 
be demonstrated if the examination of the fluid is properly 
performed. In a number of cases of general infection in 
which there was no inflammation of the meninges a diag- 
nosis has been made by means of cultures taken from the 
cerebro-spinal fluid. Finally, a number of cases of hemor- 
rhage into the brain and spinal canal have been diagnosti- 
cated by lumbar puncture. 



438 PATHOLOGICAL TECHNIQUE. 

The operation and the subsequent examination of the fluid 
should be as carefully performed as any other bacteriological 
investigation in order to obtain accurate results. The back 
of the patient and the operator's hands should be made 
sterile. The needle should be boiled for ten minutes. The 
patient should lie on the right side, with the knees drawn up, 
and with the uppermost shoulder so depressed as to present 
the spinal column to the operator. This position permits the 
operator to thrust the needle directly forward rather than 
from the side. An antitoxin needle 4 cm. in length, with a 
diameter of 1 mm., is well adapted for infants and young 
children. A longer needle is necessary for adults and chil- 
dren over ten years of age. 

Aspiration of the fluid is not necessary, but some opera- 
tors prefer to attach a hypodermic syringe to the needle to 
afford a better grasp for the hand. In this case the syringe 
would have to be detached to allow the fluid to flow. The 
additional manipulation, and possibly the defective steriliza- 
tion of the syringe, might impair the subsequent bacterio- 
logical examination. 

The puncture is generally made between the third and 
the fourth lumbar vertebrae ; sometimes between the second 
and third. The thumb of the left hand is pressed between 
the spinous processes, and the point of the needle is entered 
about 1 cm. to the right of the median line and on a level 
with the thumb-nail, and directed slightly upward and in- 
ward toward the median line. Care must be exercised to 
prevent the point of the needle from passing to the left of 
the median line and striking on the bone. At a depth of 3 
or 4 cm. in children and 7 or 8 cm. in adults the needle en- 
ters the subarachnoid space, and the fluid flows usually by 
drops. If the point of the needle meets with a bony obstruc- 
tion, it is advisable to withdraw the needle somewhat, and to 
thrust again, directing the point of the needle toward the 
median line, rather than to make lateral movements, with the 
danger of breaking the needle or causing a hemorrhage. 
The smallest quantity of blood obscures the macroscopic 
appearance of the fluid by rendering it cloudy. The fluid is 



HISTOLOGICAL METHODS. 439 

allowed to drop into an absolutely clean test-tube which pre- 
viously has been sterilized by dry heat to 150 C. and stop- 
pered with cotton. The fluid should be allowed to drop into 
the tube without running down the sides. From 5 to 15 c.c. 
of fluid is a sufficient quantity for examination. 

In meningitis there is always an exudation of cells which 
makes the fluid more or less cloudy. The degree of cloudi- 
ness is to some extent proportionate to the amount and char- 
acter of the exudation. In tubercular meningitis the amount 
of cellular exudation is sometimes so slight that the fluid 
appears clear unless examined carefully. 

Cultures on blood-serum and cover-glass preparations 
should be made from the fluid. In most cases this is best 
done from the sediment thrown down by the centrifuge. It 
is of great importance that the tube of the centrifuge should 
be clean and sterile. If tubercular meningitis is suspected, 
a guinea-pig may be inoculated with the sediment. 

The cover-glass preparations, after drying in the air, are 
best stained with Wright's blood-stain (see page 370). This 
reveals the characters of the cells very clearly and stains 
any bacteria that may be present, with the probable excep- 
tion of the tubercle bacillus. 

A predominance of polynuclear leucocytes in the sedi- 
ment means non-tubercular meningitis. The infecting bac- 
terium should be sought for and its identity determined. It 
will generally be the diplococcus intracellulars or the pneu- 
mococcus. A predominance of large and small lymphocytes 
in the sediment indicates the existence of tubercular menin- 
gitis, and cover-glass preparations should be stained for 
tubercle bacilli. It may be necessary to examine twenty or 
more preparations before finding the bacilli. 

The albumin in the fluid should be quantitated. Nor- 
mally, the cerebro-spinal fluid contains from -fa to T -J ^ of 1 
per cent, or less. In meningitis the amount is increased 
from -g 1 ^- to^ of 1 per cent., or often more. Percentages 
of albumin down to y^- of 1 per cent, can be estimated by 
the ferrocyanide-of-potassium-and-acetic-acid test and a cen- 
trifugal machine. Take 3^ c.c. of a 20 per cent, solution of 



440 PATHOLOGICAL TECHNIQUE. 

ferrocyanide of potassium, \\ c.c. of acetic acid, and 10 ex. 
of the fluid in which the albumin is to be quantitated. The 
mixture of reagents and fluid is poured into a conically- 
shaped graduated glass vessel designed for the purpose and 
centrifugalized. Sugar is rarely present and has no diag- 
nostic value. 

Ovarian and Parovarian Cysts. — The simple cysts of 
the ovary due to distention of Graafian follicles or to cystic 
change of corpora lutea, and the parovarian cysts contain a 
thin, clear, serous fluid of low specific gravity. 

The contents of the multilocular and papillary adeno-cys- 
tomata of the ovary are usually tenacious and mucous, of 
very varying specific gravity, from 1 005-1 050, but usually 
between 1020 and 1024. The fluid generally contains much 
albumin and is rich in metalbumin, which is precipitated by 
alcohol, but not by acetic acid, nitric acid, or boiling, so that 
it can readily be distinguished from mucin. Before making 
the test the albumin must be removed. 

The cyst-contents are usually yellowish, but sometimes 
may be dark-red or chocolate-colored. Microscopically, 
red and white blood-globules, occasionally blood-pigment 
and cholesterin crystals, often fat-granules and large vacu- 
olated cells, are found in the cyst fluid. Bizzozero considers 
cylindrical epithelial cells, ciliated and beaker cells, and col- 
loid concretions especially important from a diagnostic point 
of view. 

Pancreatic Cyst or Fistula.— The fluid obtained from 
a permanent fistula or large cyst of the pancreas contains 
much less solids than the normal pancreatic juice, and the 
trypsin ferment may be present in very small amount or 
possibly be entirely wanting. The fluid is colorless, alkaline 
in reaction, and has a specific gravity of about ion. It is 
characterized by three distinct properties on which its rec- 
ognition depends — namely : 

I. It splits up fat into fatty acids and glycerin. Mix to- 
gether equal parts of neutral olive oil and the alkaline fluid. 
Test with litmus-paper. Place the mixture in the incubator 
at 37 C, and test from time to time. If the fluid is pan- 



HISTOLOGICAL METHODS. AA l 

creatic, an acid reaction will be obtained in twelve to eighteen 
minutes. 

2. It transforms starch into sugar. Place in the incubator 
equal parts of a I per cent, aqueous solution of starch and 
of the fluid to be tested. In ten to twenty minutes test for 
sugar with Fehling's solution. 

3. It digests fibrin in an alkaline solution (trypsin ferment). 
Place some fibrin in the alkaline fluid and set it in the incu- 
bator. In one-half to one hour examine for peptones by 
the biuret test. Add caustic potash or soda and a few 
drops of a dilute solution of sulphate of copper. If pep- 
tones are present, a beautiful reddish-violet cofor will be 
produced. 

Dropsy of the Gall-bladder. — Puncture is generally 
not advisable. The fluid is usually colorless and mucoid or 
serous in character. All trace of biliary constituents may 
have disappeared. According to Lenhartz, numerous colon 
bacilli are usually present. 

Hydronephrosis and Renal Cysts. — The fluid is 
almost always clear as water, rarely reddish or yellow. 
Specific gravity always under 1020 (usually between 1010 
and 1015). Urea and uric acid are generally present, but 
may be absent. (Small amounts of urea are sometimes 
present in ovarian cysts.) Albumin is slight in amount. 
Microscopically, almost nothing is found. 

Echinococeus Cysts.— The fluid is perfectly clear, free 
from albumin, and contains a little succinic acid and much 
chlorid of sodium. The specific gravity varies between 1008 
and 1013. 

Microscopically, often no traces of morphological elements 
can be found. Occasionally, however, hemosiderin granules 
or cholesterin crystals occur, or the characteristic structures 
from which a positive diagnosis can be made — namely, scoli- 
ces, hooklets, or pieces of cyst-membrane. 

A positive diagnosis from a chemical examination depends 
on showing — 

1. The absence of albumin. 

2. The presence of chlorid of sodium. 



44 2 PATHOLOGICAL TECHNIQUE. 

Evaporate a drop of the fluid slowly on a slide, so as to 
get the characteristic crystals of chlorid of sodium. 

3. The presence of succinic acid. 

Acidify a little of the fluid with hydrochloric acid and 
evaporate to dryness. Extract the residue with ether. The 
crystallized material left on the evaporation of the ether, if 
dissolved in water, will give a rust-colored, gelatinous pre- 
cipitate with sesquichlorid of iron if succinic acid be present. 

Examination of the Sputum.— The secretion raised 
from the air-passages by coughing is almost invariably con- 
taminated with the secretion of the naso-pharynx and with 
particles of food from the mouth. In examinations of 
sputum these contaminations must always be borne in mind. 
The amount raised varies from a few c.c. to one or even 
several liters in twenty-four hours. 

The macroscopic appearances of the sputum depend on 
the varying proportions of mucus, pus, blood, and serum 
present. The tenacity is mainly due to the mucus. The 
reaction is usually alkaline. 

The general color, consistency, and separation into layers 
is best seen after the sputum has stood for some time in a 
tall glass. For more careful macroscopic examination small 
portions of the sputum are transferred to flat glass dishes, 
where they are spread out thinly by needles and examined 
over black or white paper. Porcelain plates painted black or 
black paper itself can be used. The latter method is con- 
venient, because the sputum can be burned up with the paper. 

The constituents of the sputum which may be recognized 
macroscopically are few in number, and not so important as 
those which may be found microscopically. 

Macroscopic Examination. — 1. Caseous Masses. — In the 
sputum from tubercular cases small, opaque, yellowish-white 
masses from the size of a pin-head to that of a small pea 
can occasionally be found, which spread out beneath a cover- 
glass like a bit of cheese. They are small caseous masses 
which are valuable for microscopic examination because they 
usually contain tubercle bacilli and elastic fibers. 

2. Fibrinous casts of the bronchioles can usually be found 



HISTOLOGICAL METHODS. 



443 



in the sputum from the third to the seventh day in cases of 
acute lobar pneumonia. They appear as yellowish-white or 
reddish-yellow threads, 2 to 3 mm. thick and \ to several 
cm. long, and are often branched. The large ones are often 
rolled into balls, and show best after being shaken in water. 
Casts of the bronchi are found in cases of fibrinous bronchitis. 
3. Curschmanris spirals (Fig. 136) of twisted threads of 
mucus enclosing epithelial cells and leucocytes occur rarely, 
except in bronchial asthma. They appear macroscopically 
as grayish-white or whitish-yellow masses or threads, \X.o \\ 




Fig. 136. — Curschmann's spirals ; a, central fiber. 



cm. 



long, and often show a visible 



mm. thick and \ to 
spiral arrangement. 

4. Dittrictis Plugs. — These are whitish-yellow masses from 
the size of a pin-head to that of a bean, which are formed in 
cases of putrid bronchitis and of gangrene of the lung. 
They have a very fetid odor, a cheesy consistency, and are 
rather easily compressed. Besides organisms they contain 
numerous fat-crystals. 

5. Shreds of tissue are found almost solely in gangrene of 
the lung, and are best recognized with the microscope. 

6. Concretions, portions of cysticercus membrane, etc., are 
rare in the secretion from the lungs. 

Microscopic Examination. — Microscopically, the sputum 
may show various kinds of cells, fragments of tissue, includ- 
ing elastic fibers, vegetable and animal parasites, and crystals. 

They will be taken up in order : 



444 PATHOLOGICAL TECHNIQUE. 

1. Red Blood-globules. — In fresh hemorrhages they appear 
normal, often in rouleaux. In old sputa many have lost 
their color. 

2. White blood-globules are almost invariably polynuclear, 
and the majority of them contain neutrophilic granules. In 
asthma, however, numerous eosinophilic and rather numer- 
ous basophilic leucocytes are regularly found. The leuco- 
cytes often contain pigment- or fat-granules. 

3. Epithelial Cells. — Pavement, cylindrical, and ciliated 
cells are found. The first come from the naso-pharynx ; the 
others usually from the trachea and bronchi, but may come 
from the nose. Desquamated alveolar epithelium is difficult 
to demonstrate. The pigmented cells found almost wholly 
in chronic passive congestion of the lungs are chiefly, 
perhaps entirely, desquamated alveolar epithelium. The 
pigment appears as yellowish, yellowish-red, or brownish- 
red granules or as yellow diffuse pigmentation. Occasion- 
ally, however, it surrounds granules of carbon, and then 
appears brownish or grayish-black. The pigment is derived 
from the blood, and will usually give the iron reaction (see 
page 403), but very young or old pigment will not. 

4. Fatty Detritus. — Fat-drops are frequently found, due to 
the fatty degeneration of cells. 




Fig. 137. — Elastic fibers (after Striimpell 



5. Elastic fibers (Fig. 137) occur singly, but more often as 
a network. They are recognized by their sharp, dark out- 
lines, due to their high degree of refractiveness, and by their 
marked degree of resistance to acids and alkalies by which 
other like tissues, such as connective-tissue fibers, are de- 



HISTOLOGICAL METHODS. 445 

stroyed. Elastic fibers are most abundant in the caseous 
masses above mentioned. When these masses cannot be 
found, the thicker portions of the sputum are squeezed be- 
tween a slide and cover-glass or between two slides, and ex- 
amined with a low power. The examination is rendered 
easier by mixing a little sputum with a 10 per cent, solution 
of caustic potash or soda. In certain cases it is necessary 
to mix together equal parts of the sputum and 10 per cent, 
caustic potash or soda, and to boil the mixture until the 
sputum is dissolved. The solution is then mixed with four 
times its own volume of water and allowed to stand for 
twenty-four hours, when the sediment can be examined for 
the elastic fibers. 

Vegetable and Animal Parasites. — Of the vegetable 
parasites, the most important is the tubercle bacillus (for its 
examination see page 184). Other bacteria sometimes ex- 
amined for are the pneumococcus, the influenza bacillus, and 
actinomyces. 

Of the animal parasites, the ameba coli is sometimes 
found secondary to an hepatic abscess which has perforated 
into the lung (see page 422). Portions of the membrane of 
an echinococcus cyst or the hooklets from the head may be 
found in the sputum, but infection with this parasite is very 
rare in this country. 

Of the crystals which occur in sputa, the most important 
are the Charcot-Leyden crystals, found mainly in bronchial 
asthma, and the crystals of the fatty acids, of cholesterin, 
and of hematoidin. Tyrosin and leucin are much more 
rare. 

The Charcot-Leyden crystals are colorless, elongated 
octahedra of varying size, soluble with difficulty in cold 
water, insoluble in alcohol, ether, chloroform, and dilute 
saline solution. 

Hematoidin crystals occur as ruby-red rhombic plates or 
columns. 

Cholesterin crystals (Fig. 1 38) occur as the well-known 
small and large rhombic plates. 

The fatty-acid crystals occur as long, pointed needles, 



446 PATHOLOGICAL TECHNIQUE. 

either singly or in groups. They are easily soluble in ether 
or hot alcohol, insoluble in water and acids. 

Examination of the Gastric Contents. — The micro- 
scopic examination of the contents of the stomach is much 
less important than the chemical. Fresh blood is easily 




FIG. 138. — Crystals of cholesterin (after Striimpell). 

recognized by the microscope. Disintegrated blood must 
be examined for chemically by the hemin test, as follows : 

Mix a little of the suspected material with a crystal or two 
of common salt, or place it on the thin layer of salt formed 
by slowly evaporating a small drop of normal salt solution 
on a slide. Cover with a cover-glass, and run in enough 
glacial acetic acid to fill up the space between slide and cover. 
Warm the slide over a flame for three-quarters to one 
minute until bubbles arise, adding more glacial acetic acid as 
evaporation takes place, until a faint reddish-brown tint 
appears. Then let the acetic acid evaporate entirely, and 
run glycerin in from the edge of the cover-glass. Micro- 
scopic examination will show dark-brown rhombic plates or 
columns of hemin if blood is present. 

Shreds of tissue or bits of mucous membrane are some- 
times found in the vomitus or removed by means of a 
stomach-tube. Examination of them in the fresh condition, 
or, more satisfactorily, in stained sections after hardening and 
imbedding, will sometimes give definite information in regard 
to the condition of the mucous membrane, or render pos- 
sible the diagnosis of a malignant growth. 



HISTOLOGICAL METHODS. 447 

Examination for Free Hydrochloric Acid. — Of the fol- 
lowing tests, that with Congo-paper is the quickest and 
easiest, but shows only that a free acid is present. To prove 
that the free acid is hydrochloric acid the phloroglucin- 
vanillin test or one of the others is necessary. 

1. Cojigo-paper is turned blue by free acids only. Free 
hydrochloric acid turns it of a cornflower-blue, a tint obtained 
with lactic acid only when in much greater concentration 
than is ever present in the stomach. Congo-paper is used 
simply by dipping it into the stomach-contents, preferably 
after filtration. 

2. Gunzburg's Test with Phloroglucin-vanillin. — The solu- 
tion consists of — 

Phloroglucin, 2 ; 

Vanillin, I ; 

Absolute alcohol, 30. 

Three or four drops of this solution are placed with an equal 
amount of the filtrate from the stomach-contents in a porce- 
lain dish and carefully heated over a small flame. Keep the 
dish in constant motion, and do not allow the mixture to 
boil, because boiling prevents the reaction from taking place. 
If free hydrochloric acid is present, a rose-red mirror is pro- 
duced. The phloroglucin-vanillin solution does not always 
keep well, so that it is best to keep alcoholic solutions of 
phloroglucin and of vanillin in separate bottles, and to mix 
together one or two drops of each when required. 

3. Boas' Resorcin Test. — The solution consists of — 

Resublimed resorcin, 5 ; 

Cane-sugar, 3 ; 

Alcohol, 94 per cent., ad 100. 

It is used in the same manner as the phloroglucin-vanillin 
test. A similar but more transient mirror is produced. 

Topfer's Dimethyl-amido-azo-benzol test is highly recom- 
mended by Simon as superior to the phloroglucin-vanillin 
test. " One or two drops of a 0.5 per cent, alcoholic solu- 



448 PATHOLOGICAL TECHNIQUE. 

tion is added to a trace of the gastric contents, which need 
not be filtered ; in the presence of free HC1 a beautiful cherry- 
red color develops, which varies in intensity according to the 
amount of free HC1 present." 

Examination of the Feces. — In examining for tape- 
worms and their eggs it is often best to dilute the feces with 
water, and then to examine the sediment both macroscopi- 
cally and under the microscope. (For ameba coli see p. 
422.) The other protozoa are best looked for in fresh slide 
preparations. 

For the cholera vibrio see p. 188 ; for the typhoid bacillus 
see p. 170. 

The membranous casts sometimes found in feces consist 
almost wholly of mucus, cylindrical epithelial cells, and 
leucocytes. Bits may be examined fresh, or the casts may 
be hardened and sections made and stained after imbedding 
in celloidin. 

Examination of the Urine. — Only those points are 
mentioned which come within the province of the patholo- 
gist. 

Of the animal parasites, the echinococcus and the filaria 
sanguinis hominis are the only important ones, and they are 
very rare (see pp. 425, 429). 

Of the vegetable parasites, tubercle bacilli and gonococci 
are the most common ; actinomycetes are very rare. 

New growths in the kidneys are accompanied with hemor- 
rhage in less than half of the cases, while new growths in 
the bladder almost invariably give rise to it. Fragments from 
new growths in the bladder are rare. A diagnosis of malig- 
nant disease from cells only is impossible. Pieces of tissue 
which show on microscopic examination the characteristic 
structure of cancer or other neoplasm must be obtained in 
order to render a diagnosis possible from the pathological 
(but not from the clinical) standpoint. 



NDEX. 



Abbe camera lucida, 239 

illuminating apparatus, 238 
Abbott's method for staining spores, 101 
Abdomen, incision to open, 28 
Abdominal cavity, inspection of, 29 
opening of, 27 

organs, removal of, 40 
Acetic acid for fat, 387 

for fresh tissue, 253 
Acid alcohol, 297 

fuchsin and hematoxylin, Pianese's, 

295 

and picro-nigrosin, Pianese's, 295 
malachite-green, and Martius 
yellow, Pianese's, 294 
and nigrosin, Pianese's, 294 
hematoxylin, Ehrlich's, 282 
method, 309 
phosphomolybdic, 284 
phosphotungstic, 284 
Actinomyces, 226 
clubs of, 228, 229 
diagnosis, 231 
Mallory's stain for, 412 
staining, 412 
Actinomycosis, 231, 234 

organism of, 226 
Adrenals, removal of, 45 
Agar-agar, glucose, preparation, 77 
glycerin, preparation, 77 
hydrocele fluid, 146 
lactose-litmus, preparation, 77 
mannite litmus, 178 
plain, precipitates in, 76 
preparation, 74 
Albumin in cerebrospinal fluid, 439 

in hydrothorax, 431 
Albuminous degenerations, 385 
Alcohol, acid, 297 
as fixative, 258 
hematoxylin, Weigert's, 284 
one-third, Ranvier's, 254 
Algeri's stains for fatty degeneration of 

nervous tissue, 354 
Alkaline methylene-blue, Unna's, 288 
Alum carmine, 285 
method, 313 
cochineal, 286 

29 



Alum cochineal method, 313 
Alum-hematein, glycerin, Mayer's, 283 
Alum-hematoxylin, 280. 281 
aqueous, method, 309 
method, 308 
Ameboid movements of plasmodium 

malariae, 417 
Amoeba coli, 422 

examination for, 422 
in dysentery, 422 
staining, 423 
differential, 423 
Amphophiles, 366 
Amputating-knives, 18 
Amyloid infiltration, 398 

Bismarck-brown for, 401 
gentian-violet for, 400, 401 
iodin for, 399 

and sulphuric acid for, 400 
iodin-green for, 400 
Langhan's method for permanent 

mounts, 399 
Mayer's stain for, 401 
methyl-violet for, 400 
stains for, 398 
Anaerobes, cultivation, 12 1 
Buchner's method, 124 
Esmarch's method, 123 
Frankel's method, 130 
in fluid media, 126 
in vacuo, 130 
Liborius' method, 122 
plate-cultures, 124 
under hydrogen, 128 

on solid media, 129 
Wright's method, 125 
in fluid media, 126 
culture-media for, 121 
Anesthetizing rabbits, 118 
Aniline and xylol as clearing reagent, 
300 
blue for nerve-fibers, Stroebe's, 339 
for nervous system, 332 
Mallory's, for connective tissue, 
322 
dyes, 286 

for bacteria in tissue, 405 
for mucin, 391 



450 



INDEX. 



Aniline oil as clearing reagent, 299 

safranin, Babes', 290 

stains, 313 

water, 297 
Aniline-fuchsin, 289 
Aniline-oil water, 297 
Animal parasites, examination for, 417 

in sputum, 445 
Animals, care of, 120 

food for, 121 

inoculation of, 99, 116 
in diagnosis, 437 
quantity of bacteria used, 120 
Anthrax bacillus, 195 

diagnosis, 198 
Aorta, opening of, 50 
Aqueous alum-hematoxylin, 281 

method, 309 
Artificial serum, 254 
Asiatic cholera, spirillum of, 188. See 

also Cotnma bacillus. 
Auricles, opening of, -x>3 
Autochthonous pigments, 402 
Autoclave for sterilization, 88 
Autopsy, 17 

cultures at, 98 

finger cuts during, 23 

general rules for, 21 

instruments for, 18 

operator's hands after, 23 

preparations, 21 

private, 24 

record of, 22 

restitution of body after, 67 

room for, 21 

rubber gloves for, 22 

suggestions to beginners, 23 

wounds during, treatment, 23 
Autopsy-bag, 24 
Autopsy-knife, 18 
Autopsy-needles, 21 
Autopsy-table, 18 
Axis-cylinder processes, stains for, 334, 

338 
Axis-cylinders of nerve-fibers, gold 
stain for, 302 

Babes' aniline safranin, 290 
Bacillus abdominalis, 163. See also 
Bacillus typhosus. 
aerogenes capsulatus, 223 
coli communis, 172 

bacillus typhosus and, differen- 
tiation, 167 
in water, 176 
colon group, 175 

comma, 188. See also Comma bacil- 
lus. 
diphtherise, 157 



Bacillus diphtheria?, diagnosis, 161 

staining, 162 

Hunt's method, 163 

toxin-production of, 160 
dysenteriae, 177 

isolation of, 179 
Friedlander's capsule, staining, 410 
lactis aerogenes, 175 
Loffler's, 157 

staining, 162 

Hunt's method, 163 

toxin-production, 160 
Lustgarten's, 416 
mallei, 209 

diagnosis, 212 
mucosus capsulatus, 216 
of anthrax, 195 

diagnosis, 198 
of bubonic plague, 202 

diagnosis, 205 
of chancroid, 213 

staining, 410 
of Ducrey, 213 
of glanders, 209. See also Glanders 

bacillus. 
of green pus, 199 
of influenza, 205 

diagnosis, 208 

staining, 408 
of Koch, 180. See also Bacilhis 

tuberculosis. 
of leprosy, 188. See also Leprosy, 

bacillus of. 
of malignant edema, 225 
of rhinoscleroma, staining, 411 
of syphilis, staining, 416 
of tetanus, 219 

toxin of, 222 
of typhoid fever, 163. See also 

Bacillus typhosus. 
paracolon, 177 
paratyphoid, 177 
pneumoniae of Friedlander, 218 
proteus, 215 
pyocyaneus, 199 
pyogenes fcetidus, 175 
smegma, staining, 416 

tubercle bacillus and, differentia- 
tion, 184 
tuberculosis, 180 

bovine and human, 183 

diagnosis, 183 

EhrlicrTs stain for, 413 

in celloidin sections, staining, 414 

in sputum, 445 

examination for, 184 

in urine, 186 

isolation of, 181 

Kiihne's method for, 414 



INDEX. 



451 



Bacillus tuberculosis, leprosy bacillus 
and, differentiation, 184 
smegma bacillus and, differentia- 
tion, 184 
staining, 413 

Ziehl-Neelson-Gabbet stain for, 
414 
typhosus, 163 

bacillus coli communis and, differ- 
entiation, 167 
blood-serum reaction, 167, 168 
clump reaction, 167, 168 
diagnosis, 167 
from blood during life, 1 70 
from feces, 170 
from rose spots, 170 
serum reaction, 167, 168 
staining, 408 
Widal reaction, 167, 168 
Bacteria, anaerobic, cultivation, 121. 
See also Anaerobes, cultivation. 
celloidin sacs in study, 115 
decolorized by Gram's method, 95 
development of, hanging-block 

method of observing, 114 
Gram-Weigert method for, 41 1 
in cultures, study of, 99 
in tissue, aniline dyes for, 405 
decolorizing agents for, 405 
imbedding, 406 

Loffler's methylene-blue for, 407 
staining, 405 
injection of, into mesenteric veins, 

118 
motility of, determination, 113 
not stained by Gram, 407 
putrefactive, 215, 216 
quantity of, used in inoculation, 120 
skin, examination for, 382 
stained by Gram's method, 95, 410 
by tubercle bacillus method, 413 
Bacteriologic examination, 89 

material for, collection of, 89 
methods, 70 
Bacteriology, special, 130 
Bacterium, isolation of impure culture 

from mixed growth, 109 
Balsam, Canada, 300 
chloroform, 300 
xylol, 300 
Band-saw, 18 
Basophiles, 366 
Baumgarten's stain for leprosy bacillus, 

415 
Benda's stain for fat acid crystals, 388 
for myoglia fibrils, 328 



for neuroglia fibrils. 



!53 



Bergamot oil as clearing reagent, 298 
Berlin blue as injection-mass, 256 



Best's carmine for glycogen, 398 
Bethe's method of fixing methylene- 
blue for nerve-fibers, 341 
Bile-pigment-bilirubin-hematoidin, 402 
Bilirubin, hematoidin-, 401 

bile-pigment-, 402 
Bionde-Heidenhain's stain, 292 

method, 317 
Bismarck-brown, 291 

for amyloid, 401 
Biuret test, 441 
Bladder, gall-, dropsy of, fluid of, 441 

opening of, 48 
Blake-Minot microtome, 244 
Blood, bacillus typhosus from, during 
life, 170 
corpuscles, counting of, 355, 361 
red. See Red corpuscles. 
white. See Leucocytes. 
cover-glass preparations, 368 
cultures during life, 98 
of gonococcus, 150 
Ehrlich's triple stain for, 369 
elements of, 364 
examination of, 354 
apparatus for, 355 

preparation of, 358 
essential details, 358 
obtaining blood for, 359 
granules of, 366 
hemoglobin in, 357 

test, 360 
in gastric contents, 446 
Leischman's stain for, 370 
leucocytes of. See Leucocytes. 
malarial organisms in, examination, 

421 
red corpuscles. Set Red corpuscles. 
specific gravity of, 354 
stains for, 369 
test for, 446 

white corpuscles of. See Leucocytes. 
Wright's stain for, 370 
Blood-counting instrument, 355 
Blood-films, staining, 372 

with Wright's stain, microscopical 
appearances in, 374 
Blood-globules, red, in sputum, 444 

white, in sputum, 444 
Blood-serum, collection of, 79 
cultures on, preparation, 96 
preparation, 79 
reaction in typhoid, 167, 168 
Blood-vessels, opening of, 39 
Blue babies, 65 

Berlin, as injection-mass, 256 
coloring mass as injection, 255 
Blut-plattchen, 367 

after Wright's stain, 375 



452 



INDEX. 



Boards for autopsy, 21 

Boas' resorcin test for hydrochloric 

acid, 447 
Body, external examination of, 26 

internal examination of, 27 

parts of, special inspection, 27 

restitution of, after autopsy, 67 
Body-length, measuring of, 26 
Boiling as fixative, 26b 
Bolton's potato-cuhures, preparation, 82 
Bone, 379 

cartilage and, differentiating, 380 

saws, 18, 20 

stains for, 380 
Bone-cutter, 21 
Bone-marrow, 377 
Borax methylene-blue, Sahli's, 289 
Bothriocephalus latus, 429 
Bottles, dropping, 252 

for histologic work, 252 
Bouillon cultures under hydrogen, 128 

glucose, preparation, 73 

preparation, 71 
Bovine tubercle bacillus, human and, 

.183 

Bowhill's method for staining flagella, 

104 
Brain, examination of, 55 
frontal section, 60 
occipital section, 60 
parietal section, 60 
pediculo-frontal section, 60 
pediculo-parietal section, 60 
prefrontal section, 60 
removal of, 50, 53 
section of, 56 

Pitre's method, 59 
Virchow's method, 58 
weight of, 55 
Bronchi, opening of, 39 
Bronchioles, fibrinous casts of, in 

sputum, 442 
Bubonic plague, bacillus of, 202 

diagnosis, 205 
Buchner's method for anaerobes, 124 

Cajal's double method for nervous 
tissue, 337 

Calcification, stains for, 404 

Calvarium, removal of, 52 

Slee's method of restitution, 68 

Camera lucida, Abbe, 239 

Canada balsam, 300 

Capsule of pneumococcus, T39 
staining, 142 

Capsule-bacillus, Friedlander's, stain- 
ing, 410 

Carbol-fuchsin, Ziehl-Neelson's, 289 

Carbol-gentian-violet, 290 



Carbolic acid and xylol as clearing re- 
agent, 299 
Carbolic-acid water, 297 
Carbon as pigment, 402, 403 
Carbon-dioxid in freezing, 239 
Carmine, alcoholic, Mayer's, 286 
alum, 285 

method, 313 
and picro-nigrosin, Pianese's, 293 
injection-mass, 255 
lithium, method, 313 

Orth's, 286 
neutral, 286 

as diffuse stain, 317 
stains, 285 

Best's, for glycogen, 398 
method, 312 
Carmine-gelatin as injection-mass, 256 
Cartilage, 379 

bone and, differentiating, 380 
stains for, 380 
Cartilage-knives, 19 
Caseation, 389 

Caseous masses in sputum, 442 
Casts of bronchioles, fibrinous, in 

sputum, 442 
Caustic potash as macerating fluid, 254 
Cedar-wood oil as clearing reagent, 299 
Celloidin, 270 
imbedding, 270 

Stepanow's method, 272 
method for serial sections, 277 
microtome, 242 
sacs in study of bacteria, 115 
sections, attaching to slides, 273 
tubercle bacillus in, staining, 414 
vulcanized fibers for mounting, 
247 
Cellulose, iodin and sulphuric acid for, 
400 
stains for, 4CO 
Central nervous system, aniline blue 
for, 332 
Cajal's double method for, 337 
chrome salts for fixing, 329 
Cox's modification of Golgi's 

stain for, 338 
degenerations of, stains for, 353 
fixing reagents for, 329 
formaldehyde as fixative, 330 
Golgi's method for, 334-337 
Cox's modification, 338 
Kallius' fixing method, 337 
Kallius' method for fixing 

Golgi's stains, 337 
Lenhossek's stain for, 334 
Nissl's stain for, 333 
phosphomolybdic-acid hematox- 
ylin for, 332 



INDEX. 



453 



Central nervous system, phosphotungs- 
tic-acid hematoxylin for, 332 
stains for, 329 
general, 331 
treatment of sections, 337 
van Gieson's stain for, 331 
Cerebrospinal fluid, albumin in, 439 
leucocytes in, 439 
meningitis, bacterium of, 153 
Chain formation, demonstration, 135 
Chancroid, bacillus of, 213 

staining, 410 
Charcot-Leyden crystals in sputum, 

445 
Children, young, autopsy on, 65 
Chisel for autopsy, 21 

hatchet-, 21 
Chlorid of gold as stain, 302 
for nerve-fibers, 338 
of iron and dinitroresorcin for nerve- 
fibers, 340 
hematoxylin, Mallory's, 31 1 
Chloroform balsam, 300 

in paraffin imbedding, 274 
Cholera, Asiatic, spirillum of, 188. 
See also Comma bacillus. 
vibrio, 188. See also Comma 
bacillus. 
Cholesterin crystals in sputum, 445 
iodin sulphuric acid for, 400 
stains for, 388 
Chrome salts for central nervous sys- 
tem, 329 
Chromic acid as macerating fluid, 254 
Circular incision for opening skull, 51 
Circulation, anomalies of, 65 
Clearing reagents, 297 

aniline and xylol as, 300 
aniline oil as, 299 
carbolic acid and xylol as, 299 
Dunham's mixture as, 299 
oil of bergamot as, 298 
of cedar-wood as, 299 
of cloves as, 299 

and thyme as, 299 
of lavender as, 299 
of thyme as, 299 
and cloves as, 299 
oleum origani cretici as, 298 
Weigert's mixtures as, 299, 300 
xylol as, 299 
Clinical pathology, 429 
Cloudy swelling, 385 
Cloves, oil of, as clearing reagent, 299 
and thyme as clearing reagent, 299 
Clubs of ray-fungus, 228, 229 
Clump-reaction of comma bacillus, 191 

of typhoid bacillus, 167, 168 
Coccidium oviforme, 425 



Cochineal, alum, 286 

method, 313 
Colloid, 393 
stains for, 393 

Unna's, 395 
Colon bacillus, 172. See also Bacillus 
coli communis. 
group, 175 
Colonies, discrete, 107 

obtaining, 109 
Colophonium, 300 
Combination stains, 292 

method, 317 
Comma bacillus, 188 

diagnosis, 192 

inoculation of guinea-pigs with, 
190 

serum reaction of, 1 91 
Concretions in sputum, 443 
Congo-paper test for hydrochloric acid, 

447 
Connective-tissue fibrillae, staining, 322 

recticulum, staining, 322 
Cork for mounting celloidin sections, 

247 
Conradi and von Drigalski's medium, 

171 
Cornea, silver staining of, 302 
Corpora amylacea, iodin and sulphuric 

acid for, 400 
Corpuscles in blood, 355, 361 
red. See Red corpuscles. 
white. See Leucocytes. 
Corrosive sublimate as fixative, 260 
Costotome, 21 
Cover-glass forceps, 92 
preparations, 92 
fixing, 92 
from cultures, 100 
from fluid media, 127 
microscopic examination, 93 
of blood, 368 

staining, 92, 94. See also Stains 
for cover-glass preparations. 
Cover-slips, 250 
cleaning, 250 
Cox's modification of Golgi's corrosive- 
sublimate method, 338 
Croupous pneumonia, bacterium of, 13S 
Crystals in sputum, 445 
Cultures, anaerobic, cultivation, 1 21. 
See also Anaerobes, cultivation. 
at autopsy, 98 
bacteria in, study of, 99 
blood, during life, 98 
cover-glass preparations from, 100 

staining, 101 
examination of, 95 
on blood-serum, 96 



454 



INDEX. 



Cultures, plate, anaerobic, 124 
Petri's, for anaerobes, 130 

pure, isolation of bacterium in, from 
mixed growth, 109 
obtaining, 107 

roll-, for discrete colonies, Esmarch's 
method, 112 

slant, 75, 79, 82, 87 

stab, 77, 86 
deep, 123 

transplanting, 107 
Culture-media, 70 

autoclave for sterilization, 88 

Dorset's egg, 182 

fluid, for anaerobes, 126 

for anaerobes, 121 

for gonococcus, 146 

for ringworms, 383 

Hiss's, for bacillus typhosus, 170 

inoculation, 107 

mannite litmus-agar, 178 

preparation, 71 

quantity in test-tubes, 86 

reaction of, titration in adjustment, 83 

Sabourand's, for ringworms, 383 

spores in, destroying, 87 

sterilization, 87 

storage of, 89 

test-tubes for, preparation, 70 

von Drigalski and Conradi's, 171 
Curschmann's spirals in sputum, 443 
Cysticerci, 429 
Cysts, echinococcus, fluid of, 441 

ovarian, fluids of, 440 

pancreatic, fluids of, 440 

parovarian, fluids of, 440 

renal, fluid of, 441 
Cytodiagnosis, 432, 433 

method, 434 

Damar, 300 

Darkschewitsch's method for serial 

celloidin sections, 278 
Death, sudden, autopsy guides, 24 

opening heart in, 35 
Decalcification, 267 

nitric acid in, 268 

phloroglucin and nitric acid in, 268 

sulphurous acid in, 269 

trichloracetic acid in, 269 
Deep stab cultures, 123 
Degenerations, albuminous, 385 

of nervous system, staining, 353 
Delafield's hematoxylin, 282 

method, 309 
Dendritic processes, stains for, 334 
Diagnosis, examination of tissues in, 

43° 

Differential stains, 306 



Diffuse stain, 291 

eosin as, method, 316 
method, 316 
neutral carmine as, 317 
picric acid as, method, 316 
van Gieson's, method, 316 
Diluting, 97 
Dimethyl-ami do-azo-benzol test for 

hydrochloric acid, 447 
Dinitroresorcin and chlorid of iron for 

nerve-fibers, 340 
Diphtheria bacilli, 157 
Diplococcus intracellularis meningi- 
tidis, 153 
diagnosis, 155 
pneumoniae, 138 
diagnosis, 141 
Discolorations, post-mortem, 26 
Discrete colonies, 107 
methods for, 109 
obtaining, 109 
Dittricrrs plugs in sputum, 443 
Dorset's egg medium, 182 
Drop-bottle on microtome, 243 
Dropping-bottle, 93, 252 
Dropsy of gall-bladder, fluid of, 441 
Ducrey's bacillus, 213 
Ductus Botalli, non-closure of, 65 
Dunham's mixture as clearing reagent, 
299 
pepton solution, preparation, 83 
Duodenum, opening of, 43 

removal of, 42 
Dura, inspection of, 53 

removal of, 53 
Dysentery, amoeba coli in, 422 
bacillus of, 177 

EAR, inspection of, 63 
Echinococcus cysts, fluid of, 441 
Edema, malignant, bacillus of, 225 
Egg medium, Dorset's, 182 
Ehrlenmeyer flasks, 87 
Ehrlich's acid hematoxylin, 282 
method, 309 
aniline-gentian-violet, 289 
method for fixing blood prepara- 
tions, 369 
for mastzellen, 320 
for tubercle bacillus, 413 
triple stain for blood, 369 
Ehrlich-Westphal method for mast- 
zellen, 320 
Elastic fibers in sputum, 444 

staining, 326 
Embolism, autopsy guides, 23 
Endothelial cells, silver staining of, 302 
Enterotome, 20 
Eosin, 291 



INDEX. 



455 



Eosin and methylene-blue in borax 
solution, Pianese's, 293 

and methylene-blue, method, 315 

as diffuse stain, method, 316 
Eosinophiles, 366, 367 

after Wright's stain, 374 
Epithelial cells in sputum, 444 
Erysipelas, 138 

bacterium of, 138 
Erythroblasts, 365 
Erythrocytes. See Red corpuscles. 
Esmarch's method for anaerobes, 123 
for roll-cultures for discrete colo- 
nies, 112 
Esophagus, removal of, 43 
Estivo-autumnal parasite, 417 

cycle, 420 
Exner's stain for myelin-sheath, 347 
External examination of body, 26 
Extraneous pigments, 402 
Exudations, acute inflammatory, 376 

examination, 431 
Eye, removal of, 62 

Farcy, bacillus of, 209 

diagnosis, 212 
Fat, 386 

acetic acid for, 387 

acid crystals, Benda's stain for, 388 

osmium for, 387 

reactions of, 386 

Scharlach R. for, 387 

stains for, 386 

Sudan III. for, 387 

tests for, 386 
Fatty degeneration of myelin-sheath, 
stains for, 354 
of nerve-fibers, stains for, 354 

detritus in sputum, 444 
Fatty-acid crystals in sputum, 445 
Feces, bacillus typhosus from, 170 

examination of, 448 
Fermentation-tube, 175 
Ferric salts, reaction for, 404 
Ferrous salts, stains for, 404 
Fetus, age of, 67 

monthly length of, 66 
weight of, 66 
Fibers, elastic, in sputum, 444 
Fibrillae, connective tissues, staining, 

322 
Fibrils, fibroglia, staining, 324 
Fibrin, 389 

stains for, 389, 390 
Fibrino-serous exudations, examination, 

431 

Fibroglia fibrils, staining, 324 
Filaria Bancrofti, 425 
sanguinis hominis, 425 



Fistula, pancreatic, fluids of, 440 

Fixing cover-glass preparations, 92 
reagents, 257 
alcohol as, 258 

Bethe's, for methylene-blue, 341 
boiling as, 266 
choice, 257 

corrosive sublimate as, 260 
Flemming's solution as, 258, 261 
for central nervous system, 329 
formaldehyde as, 258, 262 

for central nervous system, 330 
for frozen sections, 263 
Hermann's solution as, 262 
Kallius', for Golgi's stains, ^yj 
Marchi's fluid as, 267 
Miiller's fluid as, 266 
Orth's fluid as, 258, 261 
Pianese's solution as, 262 
Tellyesniczky's mixture as, 267 
Wright's, for frozen sections, 263 
Zenker's fluid as, 258, 259 
special organs, 375 

Flagella, staining, 102 

Bowhill's method, 104 
Loffler's method, 103 
Neuman's method, 105 
Pitfield's method, modified by 

Smith, 104 
Smith's modification of Pitfield's 

method, 104 
Williams' method, 105 

Flasks, Ehrlenmeyer, 87 

Flemming's solution as fixative, 261, 
288 

Flexner's method for leprosy bacillus, 

415 

Fluid media, anaerobic cultivation in, 

126 
Fluids, collection of, 91 

examination of, 254 

indifferent, 254 

macerating, 254 

obtained by puncture, examination, 

431 
Food for animals, 1 21 
Forceps, cover-glass, 92 

for autopsy, 21 
Formaldehyde as fixative, 258, 262 
for central nervous system, 330 
for frozen sections, 263 
Formic-acid method, Lowit's, 303 

Ranvier's, 303 
Frankel's method for anaerobes, 130 
Free hydrochloric acid, tests for, 447 
Freezing, carbon-dioxid for, 239 
microtome, 239 
knife for, 241 
Mixter's method, 239 



456 



INDEX. 



Fresh tissue, acetic acid treatment, 253 
examination of, 252 
hydrochloric acid for, 254 
indifferent fluids for, 254 
macerating fluids for, 254 
osmic acid for, 253 
Scharlach R. for, 254 
sections of, 252 
staining, 252 
Sudan III. for, 254 

Freund's gold stain for nerve fibers, 

339 

Friedlander's bacillus pneumoniae, 218 

capsule-bacillus, staining, 410 
Frozen sections, consistence of tissue, 
242 
cutting, 241 

fixing, Wright's method, 263 
imbedding, Wright's method, 279 
Fuchsin, 289 

acid, and hematoxylin, Pianese's, 

295 
and picro-nigrosin, Pianese's, 295 
malachite-green, and Martius 

yellow, Pianese's, 294 
malachite-green, and nigrosin, 
Pianese's, 294 
aniline-, 289 

carbol-, Ziehl-Neelson's, 289 
picro-, van Gieson's, 291 
Fungi, skin, examination for, 382 
Fungus-foot, 232 

Gabbet's methylene-blue, 288 
Gabbet-Ziehl-Neelson method for 

tubercle bacillus, 414 
Gall-bladder, dropsy of, fluid of, 441 
Ganglion-cells, stains for, 334 
Gangrenous exudations, examination, 

43i>43 2 
Gas-production of bacillus aerogenes 

capsulatus, 224 
Gastric contents, blood in, 446 
chemical examination, 446 
examination, 446 
hemin test, 446 
hydrochloric acid in, 447 
microscopic examination, 446 
tissue shreds in,' 446 
Gastro-intestinal tract, 378 

inspection of, 41 
Gelatin, carmine-, as injection, 256 
glucose, preparation, 79 
plain, preparation, 78 
Gentian-violet, 289 
carbol-, 290 
for amyloid, 400, 401 
for glycogen, Lubarsch's, 397 
Stirling's, 289 



Gerlach's gold stain for nerve-fibers, 

339 
Giacomi's method for syphilis bacillus, 

416 
Gigantoblasts, 365 
Glanders bacillus, 209 
diagnosis, 212 

Loffler's methylene-blue fur, 409 
Noniewicz's method for, 409 
Schultze's method for, 409 
staining, 409 
tubercles, 211 
Glucose agar-agar, preparation, 77 
bouillon, preparation, 73 
gelatin, preparation, 79 
Glycerin agar-agar, preparation, 77 
Glycerin-albumin mixture, Mayer's, 

297 
Glycerin - alum - hematein solution, 

Mayer's 
Glycogen, 396 

Best's carmine for, 398 
Langhan's iodin for, 397 
Lubarsch's gentian-violet for, 397 

iodin hematoxylin for, 397 
stains for, 396-398 
Gold as stain, 302 

for nerve-fibers, 338 
Golgi's corrosive-sublimate method, 
Cox's modification, 338 
stains for nervous tissues, 334-337 
Cajal's modification, 337 
fixing of, 337 
Kallius' fixative, 337 
Gonococcus, 145 
blood cultures, 150 
culture-media for, 146 
diagnosis, 148 
Gram's method for, 148 
staining, 148, 150, 408 
staphylococcus pyogenes and, differ- 
entiation, 148 
streutococcus and, differentiation, 
' 148 
Gonorrhea, bacterium of, 145 
Gram's method, 410 

bacteria decolorized by, 95 
not stained by, 407 
stained by, 95, 410 
for cover-glass preparations, 94 

from cultures, 101 
for gonococci, 148 
Gram- Weigert method for bacteria, 41 1 
Granulation-tissue, 376 
Granules of blood, 366 
Green pus, bacillus of, 199 
Grippe, bacillus of, 205 
Guinea-pigs, care of, 121 
food for, 121 



INDEX. 



457 



Guinea-pigs, inoculation of, 116 
in surgical tuberculosis, 187 
intraperitoneal, 1 17 
subcutaneous, 1 16 
with comma bacillus, 190 

Gunzburg's test for hydrochloric acid, 
447 

Hair, examination of, 382 

protection of, at autopsy, 51 
Hammer, soft-iron, 21 

steel, 21 
Hammerschlag's method for specific 

gravity of blood, 354 
Hanging drop, 113 
preparation, 113 
spore -formation and, 114 
Harke's method for inspection of naso- 
pharynx, 64 
Harris' method for celloidin sacs, 1 15 
Hatchet-chisel, 21 
Head-holder, 21 

Heart, inspection of, external, 32 
opening of, 33 

after sudden death, 35 
removal of, 33, 36 
size of, 36 
weight of, 36 
Heidenhain's hematoxylin stains, 
method, 310 
iron hematoxylin, method, 311 
Heller's stain for myelin -sheath, 347 

Robertson's modification, 348 
Hemalum, Mayer's, 283 

method, 310 
Hematein solution, glycerin -alum-, 
Mayer's, 283 
stains, 280 
Hematoblasts, 364, 367 
Hematogenous pigments, 401 
Hematoidin, bile - pigment-bilirubin-, 
402 
crystals in sputum, 445 
Hematoidin-bilirubin, 401 
Hematoxylin, acid, Ehrlich's, 282 
method, 309 
phosphomolybdic, 284 
phosphotungstic, 284 
alcohol, Weigert's, 284 
alum, 280, 281 
method, 308 
alum-aqueous, method, 309 
and acid fuchsin, Pianese's, 295 
and light green, Pianese's, 295 
Delafield's, method, 309 
Heidenhain's, method, 310 
iodin-, Lubarsch's, for glycogen, 397 
iron chlorid, Mallory's, method, 311 
Heidenhain's, method, 311 



Hematoxylin, phosphomolybdic-acid, 
for nervous system, 332 
phosphotungstic-acid, for nervous 
system, 332 
for neuroglia-fibers, 352 
stains, 280 
Hemin test, 446 

Hemocytometer, Thoma-Zeiss, 355 
Hemoglobin, 401 
in blood, 357 
test, 360 
Hemometer, von Fleischl's, 357 
Hemorrhage from stomach, autopsy 

guides, 23 
Hemorrhagic exudation, examination, 

431 

Hemosiderin, 402 

iron in, reaction for, 403 
Hemp twine, 21 

Hermann's solution as fixative, 262 
Hill's hanging-block method for observ- 
ing development of bacteria, 114 
Hiss's medium for bacillus typhosus, 

170 
Histological methods, 237 
Hobb's tea infuser, 251 
Holder, head-, 21 
Hollow slide, 1 13 
Honing, 248 

Hoyer's thionin for mucin, 392 
Hunt's method for bacillus diphtheria?, 

163 
Hyaline, 393 
stains for, 393 
Unna's, 395 
Hydrocele fluid agar, 146 
Hydrochloric acid for fresh tissue, 254 
Hydrogen, cultures under, bouillon, 
128 
on solid media, 129 
Petri's method, 130 
generation, 129 
Hydronephrosis, fluid of, 441 
Hydrophobia, 235 

diagnosis, 236 
Hydrothorax, albumin in, 431 
Hypodermic syringe for collecting fluid 
material, 91 

Illuminating apparatus, Abbe, 238 
Illumination for microscopic work, 239 
Imbedding, celloidin, 270 
Stepanow's method, 272 
for bacteria in tissue, 406 
paraffin, 270, 274 
processes, 269 

for frozen sections, Wright's. 270 
Impregnations, metallic, 301. See also 
Metallic stains. 



458 



INDEX. 



Incisions for opening heart, ^ 
to bare thorax, 28, 30 
to open abdomen, 28 
Indifferent fluids, 254 
Inferior vena cava, opening of, 49 
Inflammatory exudations, 376 
Influenza, bacillus of, 205 
staining, 408 
diagnosis, 208 
Injections, 255 

Berlin blue as, 256 
blue coloring as, 255 
carmine as, 255 
carmine-gelatin as, 256 
cold, 255 
warm, 256 
Inoculation of animals, 99, 1 16 
for diagnosis, 437 
quantity of bacteria used, 120 
of guinea-pigs, 116 

in surgical tuberculosis, 187 
intraperitoneal, 1 17 
subcutaneous, 1 16 
with comma bacillus, 190 
of media, 107 
of mice, 119 
of rabbits, 1 17 
intravenous, 117 
Inoscopy, 433> 43 6 

Instruments for postmortem examina- 
tion, 18 
metal, for histologic work, 251 
Internal examination of body, 27 
Intestine, 378 
opening of, 43 
removal of, 42 
Intraperitoneal inoculation of guinea- 
pigs, 117 
Intravenous inoculation of rabbits, 

117 
Iodin and sulphuric acid for amyloid, 
400 
for cellulose, 400 
for cholesterin crystals, 400 
for corpora amylacea, 400 
for starch granules, 400 
as stain, 296 
for amyloid, 399 

Langhan's method for permanent 
mounts, 399 
Langhan's, for glycogen, 397 
Iodin-green for amyloid, 400 
Iodin-hematoxylin, Lubarsch's, for 

glycogen, 397 
Iron as pigment, 402, 403 

hematoxylin, chlorid of, Mallory's, 
method, 311 
Heidenhain's, method, 311 
in hemosiderin, reaction for, 403 



Iron-alizarin-toluidin-blue for neurog- 
lia fibrils, 353 

Isolation of bacterium in pure culture 
from mixed growth, 109 

Jaundice, opening duodenum in, 43 

removal of liver in, 44 
Jousset's method for tubercle bacillus 
in serous fluids, 433, 436 

Kaiserling's method to preserve 
natural colors in museum prep- 
arations, 384 
Kallius' fixing method for Golgi's 

stains, 337 
Karyomitosis, staining for, 318 
Keratohyalin, 396 
Kidney, 378 

new growths in, urine indications, 

448 
removal of, 45 
size, 47 
weight, 47 
Knives, amputation, 18 
autopsy, 18 
cartilage, 19 
for cutting sections, 241 
microtome, 248 
Koch's bacillus, 180. See also Bacil- 
lus tuberculosis. 
method for diagnosing Asiatic 
cholera, 193 
for inoculation of guinea-pigs with 
comma bacillus, 191 
Kiihne's method for tubercle bacillus, 
414 
methylene-blue, 288 

Laboratory outfit, 237 
Lactose-litmus agar-agar, preparation, 

Langhans' iodin for glycogen, 397 
method for permanent mounts of 
amyloid with iodin, 399 
Lavender oil as clearing reagent, 299 
Leischman's stain for blood, 370 
Lenhossek's stain for tigroid bodies, 

334 
Lens, oil-immersion, 238 
Leprosy, bacillus of, 188 

Baumgarten's stain for, 415 
Flexner's stain for, 415 
staining, 415 

tubercle bacillus and, differentia- 
tion, 184 
Leucocytes, 365 
estimation, 364 
in blood, 355 
in cerebrospinal fluid, 439 



INDEX. 



459 



Leucocytes, varieties, 366 
Liborius' method for anaerobes, 122 
Light green and hematoxylin, Pianese's, 

295 
Lithium carmine, method, 313 

Orth's, 286 
Litmus-milk, preparation, 82 
Liver, 378 

removal of, 44 
size of, 45 
weight of, 45 
Lobar pneumonia, bacterium of, 138 
Loffler's bacillus, 157 
staining, 162 

Hunt's method, 163 
toxin-production, 160 
method for staining flagella, 103 
methylene-blue, 288 
for bacteria, 407 
for glanders bacillus, 409 
mixture, preparation, 79 
Loop, platinum, 96 
Lowit's formic-acid method, 303 
Lubarsch's gentian-violet for glycogen, 

397 

iodin-hematoxylin for glycogen, 397 
Luer's double rachiotome, 20 
Lugol's solution, 296 
Lumbar puncture, 437 
Lung, 377 

incisions into, 3$ 

inspection of, 32 

removal of, t>7 
Lustgarten's bacillus, 416 

method for syphilis bacillus, 416 
Lymphocytes, 366 

after Wright's stain, 374 

Macerating fluids, 254 
Madura foot, 232 

melanoid, 233 

ochroid, 233 
Malachite-green, acid fuchsin, and 

nigrosin, Pianese's, 294 
Malarial organisms, 417 

ameboid movements, 417, 418 

changes in, 418 

cycle, 418 

development, 417 

double infections, 420 

estivo-autumnal, 417 
cycle, 420 

in blood, examination, 421 

pigment in, 417 

quartan, 417 
cycle, 419 

Romanowsky's method for, 370, 

371, 421 
segmentation of, 417, 418 



Malarial organisms, tertian, 417 
cycle, 418 
varieties, 417 
Wright's stain for, 421 
Malignant edema, bacillus of, 225 
Mallory's aniline-blue for connective- 
tissue, 322 
chlorid of iron hematoxylin, method, 

311 

stain for actinomyces, 412 
for fibroglia fibrils, 325, 329 
for neuroglia fibers, 349 
Mall's stain for reticulum, 324 
Mannite litmus-agar, 178 
Marchi's fluid as fixative, 267 

stain for fatty degeneration of nerv- 
ous tissue, 354 
Markzellen, 367 

after Wright's stain, 375 
Marrow, inspection of, 50 

bone, 377 
Martius yellow, malachite-green, and 

acid fuchsin, Pianese's, 294 
Mastzellen, 367 

after Wright's stain, 375 

stains for, 320 
Mayer's alcoholic carmine, 286 

glycerin-albumin mixture, 297 

glycerin-alum-hematein solution, 283 

hemalum, 283 
acid, 283 
method, 310 

muchematein, 283 

stain for amyloid, 401 
Mechanical stage for microscope, 239 
Medulla lesions in rabies, 236 
Megaloblasts, 365 
Megalocytes, 365 
Melanin, 402 
Melanoid mycetoma, 233 
Meningitis, bacterium of, 153 

diagnosis, 155 
Mesenteric veins, injection of bacteria 

into, 118 
Mesentery, removal of, 42 
Metal instruments for histologic work, 

251 
Metallic stains, 301 
gold as, 302 
osmic acid as, 303 
osmium tetroxid as, 303 
perosmic acid as, 303 
silver as, 301 
Methemoglobin, 401 
Methylene-blue, 287 
alkaline, Unna's, 288 
and eosin in borax solution, Pianese's, 

293 

method, 315 



460 



INDEX. 



Methylene-blue, borax, Sahli's, 289 
for nerve-fibers, 340 
Kiihne's, 288 
Loffler's, 288 
for bacteria, 407 
for glanders bacillus, 409 
polychrome, Unna's, 288 

for mucin, 392 
Sahli's borax, 289 
Methyl-green and pyronin mixture, 
Pappenheim's, for cover-glass 
preparations, 94 
Methyl-violet, 290 
for amyloid, 400 
Mice, care of, 121 
food for, 121 
inoculation of, 119 
Micrococcus catarrhalis, 151 
lanceolatus, 138 
diagnosis, 141 
of sputum-septicemia, 138, 140 

diagnosis, 1 41 
pneumoniae crouposae, 138 
tetragenus, 152 
Microcytes, 365 
Microscopes, 237 

Microscopic examination of cover- 
glass preparations, 93 
Microtome, celloidin, 242 
drop-bottle on, 243 
freezing, 239 

knife for, 241 
knives, 248 
Minot's, 243 
wheel, 246 
Minot-Blake, 244 
paraffin, 246 
Middle ear, inspection of, 63 
Milk, litmus-, preparation, 82 
Minot microtome, 243 

wheel microtome, 246 
Minot-Blake microtome, 244 
Mitosis, 318 

Mixter's freezing method, 239 
Moeller's method for staining spores, 

101 
Mononuclear leucocytes, 366 
after Wright's stain, 374 
Morris' stain for skin parasites, 383 
Motility of bacteria, determination, 113 
Mounting reagents, 300 
Mouse-holder, 1 19 
Muchematein, Mayer's, 283 
Mucin, 390 

aniline dyes for, 391 
Hoyer's thionin for, 392 
pseudo-, 392 
stains for, 391 
test for, 391 



Mucin, Unna's polychrome methylene- 
blue for, 392 
Miiller's fluid as fixative, 266 
Muscle-cells, smooth, staining, 328 

striated, staining, 328 
Museum preparations, 384 

natural colors of, preserving, 384 
Mycetoma, 232 

melanoid, 233 

ochroid, 233 
Myelin-sheath, Exner's stain for, 347 

fatty degeneration of, stains for, 354 

Heller's stain for, 347 

Robertson's modification, 348 

stains for, 342 

Weigert's stain for, 343 

Pal's modification, 345 
Myelocytes, 367 

after Wright's stain, 375 
Myelotome, 18 
Myoglia fibrils, Benda's stain for, 328 

Nasopharynx, inspection of, 64 
Neck, block for, at autopsy, 21 

organs of, removal of, 39 
Necrosis, 388 
Needles, autopsy-, 21 
Neelson-Gabbet-Ziehl method for 

tubercle bacillus, 414 
Neissers method for bacillus diph- 
theria?, 162 
Nerve-fibers, aniline-blue for, 339 

axis-cylinders of, gold stain for, 302 

chlorid of iron and dinitroresorcm 
for, 340 

fatty degeneration of, stains for, 354 

gold stain for, 23^ 

methylene-blue for, 340 

myelin-sheath of, stains for, 342 
Nervous system, central. See Central 

ne? vous system. 
Neuman's method for staining flagella, 

105 

Neuroglia fibrils, Benda's stain for, 353 

iron-alizarin-toluidin for, 353 
Neuroglia-fibers, Mallory's stain for, 

349 
phosphotungstic acid hematoxylin 

for, 352 
stains for, 348 
Weigert*s stain for, 350 
Neutral carmine, 286 

as diffuse stain, 317 
Neutrophil es, 366, 367 

polynuclear, after Wright's stain, 374 
New practical staining dish, 251 
New-born, examination of, 65 

weight of organs in, 67 
Nigrosin for nervous tissue, 333 



INDEX. 



461 



Nigrosin, malachite-green, and acid 

fuchsin, Pianese's, 294 
Nissl, stains for, 333 t 
Nitrate of silver as stain, 301 
Nitric acid and phloroglucin in decal- 
cification, 268 
in decalcification, 268 
Noniewicz's method for glanders bacil- 
lus, 409 
Normoblast, 365 
Nuclear stains, 308 

alum-hematoxylin as, 308 

aqueous, 309 
aniline dyes as, 313 
carmine, 312 

combination, method, 317 
Delafield's hematoxylin, 309 
Ehrlich's acid hematoxylin, 309 
Heidenhain's hematoxylin, 310, 

311 

hematoxylin, 309, 310, 31 1 
Mallory's chlurid of iron hema- 
toxylin, 311 
Mayer's hemalum, 310 
Nutrition, general, in autopsy, 26 

Ochroid mycetoma, 233 
Oil, aniline, as clearing reagent, 299 
of bergamot as clearing reagent, 298 
of cedar in paraffin imbedding, 274 
of cedar- wood as clearing reagent, 

299 
of cloves and thyme as clearing re- 
agent, 299 
as clearing reagent, 299 
of lavender as clearing reagent, 299 
of thyme as clearing reagent, 299 
and cloves as clearing reagent, 299 
Oil-immersion lens, 238 
Olein, 386 

Oleum origani cretici as clearing re- 
agent, 298 
Orbit, examination of contents, 62 
Orcein, 296 

Orth's discharging fluid, 297 
fluid as fixative, 258, 261 
lithium carmine, 286 
Osmic acid as stain, 303 
for fresh tissue, 253 
Osmium for fat, 387 

tetroxid as stain, 303 
Ovarian cysts, fluid of, 440 
Ovaries, opening of, 48 

weight of, 48 
Oxygen, cultivation without, 121 

Palmitin, 386 

Pal's modification of Weigert's myelin- 
sheath stain, 345 



Pancreas, cross-sections of, 44 

removal of, 42 
Pancreatic cysts, fluid of, 440 
Pappenheim's pyronin and methyl- 
green mixture for cover-glass 
preparations, 94 
Paracarmine, 286 
Paracolon bacillus, 177 
Paraffin bath, 246 
imbedding, 270, 274 
method for serial sections, 276, 279 
microtome, 246 

sections, attaching to slides, 297 
cutting, 276 
Parasites, animal, examination, 417 
in sputum, 445 
estivo-autumnal, 417 

cycle, 420 
quartan, 417 
cycle, 419 
tertian, 417 
cycle, 418 
vegetable, in sputum, 445 
Paratyphoid bacillus, 177 
Parhemoglobin, 401 
Parovarian cysts, fluid in, 440 
Pathological fluids, collection of, 91 
material, collection of, for examina- 
tion, 89 
products, 385 
Pathology, clinical, 429 
Pelvic organs, removal of, 47 
Penis, removal of, 49 
Pepton solution, Dunham's, prepara- 
tion, 83 
Pericardium, opening of, 32 
Peritonitis, acute, autopsy guides, 23 
Perosmic acid as stain, 303 
Petri dishes, no 

oblong rectangular, 251 
method for anaerobes under hydro- 
gen, 130 
for discrete colonies, 1 10 
plate method for isolation of bac- 
terium, no 
Petrifaction, stains for, 404 
Petrous bone, removal of, 63 
Pfeiffer's method for inoculation of 
guinea-pigs with comma bacil- 
lus, 190 
phenomenon, 191 
Phenolphthalein as indicator in adjust- 
ment of reaction, 84 
Phloroglucin and nitric acid in decal- 
cification, 268 
Phloroglucin-vanillin test for hydro- 
chloric acid, 447 
Phosphomolvbdic acid hematoxvlin, 
284 ' 



462 



INDEX. 



Phosphomolybdic acid for nervous sys- 
tem, 332 
Phosphotungstic acid hematoxylin, 284 
for nervous system, 332 
for neuroglia fibers, 352 
Pia, removal of, 56 

stripping off of, 55 
Pianese's acid fuchsin and hematoxylin, 

and picro-nigrosin, 295 
carmine and picro-nigrosin, 293 
hematoxylin and light green, 295 
malachite-green, acid fuchsin, and 
Martius yellow, 294 
and nigrosin, 294 
methylene-blue and eosin in borax 

solution, 293 
solution as fixative, 262 
stains, 293 
Picric acid as stain, 291 

method, 316 
Picro-fuchsin, van Gieson's, 291 
Picro-nigrosin, 292 

and acid fuchsin, Pianese's, 295 
and carmine, Pianese's, 293 
Pigments, 401 

autochthonous, 402 
extraneous, 402 
hematogenous, 401 
Pitfield's method for staining flagella, 

Smith's modification, 104 
Pitre's section of brain, 59 
Plague, bubonic, bacillus of, 202 

diagnosis, 205 
Plain agar-agar, precipitates in, 76 
preparation, 74 
gelatin, preparation, 78 
Plasma-cells, staining, 321 
Plasmodium malariae, 417. See also 

Malarial organisms. 
Plate method, Petri's, for discrete 

colony, no 
Plate-cultures, anaerobic, 1 24 

Petri's, for anaerobes, 1 30 
Platinum wire, 96 
Pleural adhesions, 32, 37 

cavities, inspection of, 31 
Pneumococcus, 138 
capsule of, 139 
staining, 142 
diagnosis, 141 

streptococcus and, differentiation, 135 
Pneumonia, bacterium of, 138 

diagnosis, 141 
Poikilocytosis, 365 
Polychrome methylene-blue, Unna's, 

288 
Polymorphonuclear leucocyte, 366, 
367 



Postmortem discolorations, 26 

examinations, 17. See also Autopsy. 

rigidity, 26 
Potash, caustic, as macerating fluid. 254 
Potato-cultures, Bolton's, preparation, 

82 
Precipitates in agar-agar, 76 
Primary anterior incision, 28 
Private autopsy, 24 
Probes, 21 
Proteus group, 216 

mirabilis, 216 

vulgaris, 215 

Zenkeri, 216 
Protoplasm of cells, gold stain for, 302 
Pseudo-mucin, 392 
Puncture fluids, examination, 431 

lumbar, 437 
Pure culture, isolation of bacterium in, 
from mixed growth, 109 
obtaining of, 107 
Purulent exudations, examination, 431, 

432 
Pus, green, bacillus of, 199 
Putrefaction, bacteria of, 215, 216 
Putrid exudations, examination, 431, 

43 2 
Pyronin and methyl-green mixture, 
Pappenheim's, for cover-glass prepa- 
rations, 94 

Quartan parasite, 417 
cycle, 419 

Rabbits, anesthetizing, 118 
care of, 121 
food for, 121 
inoculation of, 117 
intravenous, 1 17 
Rabies, 235 

diagnosis, 236 
Rachiotome, double, Luer's, 20 
Ranvier's formic-acid method, 303 

macerating fluid, 254 
Ravaut's method for examination of 

serous fluids, 432, 433 
Ray-fungus, 226 

clubs of, 228, 229 
Reaction of culture-media, titration in 

adjustment, 83 
Rectum, opening of, 48 

removal of, 48 
Red blood -corpuscles, 364 
after Wright's stain, 374 
anemic degeneration of, 365 
estimation, 361, 364 
in blood, 355 
blood-globules in sputum, 444 
nucleated, 365 



INDEX. 



463 



Renal cysts, fluid of, 441 

Resorcin test, Boas', for hydrochloric 

acid, 447 
Respiration, determination of act oc- 
curring, 66 
Reticulum, staining, 322 
Rhinoscleroma, bacillus of, staining, 

411 
Ribbons of sections, 276, 279 
Rigidity, postmortem, 26 
Ringworms, medium for, 383 
Ripening, 280 
Robertson's modification of Heller's 

myelin-sheath stain, 348 
Roll-cultures for discrete colonies, 

Esmarch's method, 112 
Romanowsky's method for malarial 

organisms, 370, 371, 421 
Rose spots, bacillus typhosus from, 170 
Round worms, 425 
Rubber gloves for autopsy, 22 
Running water for washing specimens, 

249 

Sabourand's medium for ringworms, 

383 
Safranin, 290 

aniline, Babes', 290 

as nuclear stain, method, 314 

for karyomitotic staining, 319 

Schaffer's, for differentiating bone 

from cartilage, 380 
Sahli's borax methylene-blue, 289 
Saw, bone, 18, 20 
Scales for autopsy, 18 
Scalpels, 19 
Schaffer's safranin for differentiating 

bone from cartilage, 380 
Schallibaum's solution, 297 
Scharlach R. for fat, 387 

for fresh tissue, 254 
Schering's celloidin, 270 
Schmorl's method of differentiating 

bone from cartilage, 380 
Schultz's method for glanders bacillus, 

409 
Scissors, 19 
Sedimentation for tubercle bacillus in 

sputum, 185 
Segmentation of plasmodium malarias, 

417 

Semilunar ganglia, location, 49 
Septicemia, sputum-, micrococcus of, 

138, 140 
Serial sections, celloidin, 277 

paraffin, 276, 279 
Sero-fibrinous exudations, examination, 

431 
Serous exudations, examination, 431 



Serous fluids, examination, 432 

tubercle bacillus in, inoscopy for, 

43 6 

Serum, artificial, 254 
blood-, collection of, 79 
cultures on, 96 

preparation, 96 
preparation, 79 
reaction in typhoid, 167, 168 
reaction of bacillus typhosus, 167, 
168 
of comma bacillus, 191 
Shiga bacillus, 177 
Silver as pigment, 402 

as stain, 301 
Simple anaerobic plate-cultures, 124 
staining of cover-glass preparations, 

94 

Skeleton, development of, 26 
Skin, condition of, in autopsy, 26 
parasites of, staining, 383 
staining, 382 
Skull, infant's, opening of, 52 

opening of, 51 
Slant culture, 75, 79, 82, 87 
Slee's restitution of calvarium, 68 
Slides, 250 

attaching celloidin sections to, 273 

paraffin sections to, 297 
cleaning, 250 
hollow, 113 
old, cleaning, 250 
Smegma bacillus, staining, 416 

tubercle bacillus and, differentia- 
tion, 184 
Smith's method for bacillus coli com- 
munis in water, 177 
for staining capsule of pneumo- 
coccus, 142 
modification of Pitfield's method for 
staining flagella, 104 
Smooth muscle-cells, staining, 328 
Spatulas, 251 
Special bacteriology, 130 
organs, examining, 375 

freezing, 375 
stains, 320 
Specific gravity of blood, 354 

of puncture fluids, 431 
Spinal column, removal of, 50 
cord, removal of, 60 
lesions in rabies, 236 
Spirals, Curschmann's, in sputum, 443 
Spirillum of Asiatic cholera, 188. See 

also Comma bacillus. 
Spleen, 377 

removal of, a I 
Spores, formation of, hanging drop in 
study, 114 



464 



INDEX. 



Spores in media, destroying, 87 
staining, 101 

Abbott's method, 101 
Moeller's method, 101 
vitality of, 87 
Sporozoa, 425 

Sputum, animal parasites in, 445 
blood-globules in, 444 
caseous masses in, 442 
cells in, 444 

Charcot-Leyden crystals in, 445 
cholesterin crystals in, 445 
concretions in, 443 
crystals in, 445 
Curschmann's spirals in, 443 
Dittrich's plugs in, 443 
elastic fibers in, 444 
epithelial cells in, 444 
examination of, 442 
fatty detritus in, 444 
fatty-acid crystals in, 445 
fibrinous casts of bronchioles in, 442 
hematoidin crystals in, 445 
influenza bacilli in, 208 
macroscopic appearance, 442 
microscopic examination, 443 
parasites in, 445 
tissue shreds in, 443 
tubercle bacilli in, 445 

examination for, 184 
vegetable parasites in, 445 
Sputum-septicemia, diagnosis, 141 

micrococcus of, 138, 140 
Stab culture, 77, 86 

_ deep, 123 
Staining, 304. See also Stains. 
differentiation by, 306 
dishes, 250 
concave, 251 
Hobb's tea infuser, 251 
new practical, 251 
Petri's oblong rectangular, 251 
in mass, 317 
methods, 304 
steps in, 307 
Stains. 280 

acetic acid, for fat, 387 
acid hematoxylin, Ehrlich's, 282 
method, 309 
phosphomolybdic, 284 
phosphotungstic, 284 
alcoholic carmine, Mayer's, 286 

hematoxylin, Weigert's, 284 
Algeri's, for fatty degeneration of 

nervous tissue, 354 
alum cochineal, 286 
method, 313 
carmine, 285 
method, 313 



Stains, alum-hematoxylin, 280, 281, 
308 
aqueous, method, 309 
method, 308 
aniline, 286, 313 

blue for nervous system, 332 

Stroebe's, 339 
for bacteria in tissue, 405 
for mucin, 391 
safranin, Babes', 290 
aniline-fuchsin, 289 
aniline-gentian-violet, Ehrlich's, 289 
Babes' aniline safranin, 290 
Baumgarten's, for leprosy bacillus, 

415 
Benda's, for fat acid crystals, 388 
for myoglia fibrils, 328 
for neuroglia fibrils, 353 
Best's carmine, for glycogen, 398 
Biondi-Heidenhain's, 292 

method, 317 
Bismarck-brown, 291 

for amyloid, 401 
Cajal's double method for nervous 

tissue, 337 
carbol-fuchsin, Ziehl-Neelson's, 289 
carbol-gentian-violet, 290 
carmine, 285 

alcoholic, Mayer's, 286 
alum, 285 

method, 313 
Best's, for glycogen, 398 
lithium, Orth's, 286 
method, 312 
neutral, 286 
chlorid of gold as, 302 
for nerve-fibers, 338 
of iron and dinitroresorcin for 
nerve-fibers, 340 
cochineal alum, 286 

method, 313 
combination, 292 

Cox's modification of Golgi's corro- 
sive-sublimate method, 338 
Delafield's hematoxylin, 282 

method, 309 
differential, 306 
diffuse, 291 
dinitroresorcin and chlorid of iron 

for nerve-fibers, 340 
Ehrlich's acid hematoxylin, 282, 309 
method, 309 
aniline-gentian-violet, 289 
for mastzellen, 320 
for tubercle bacillus, 413 
triple, for blood, 369 
Ehrlich-Westphal, for mastzellen, 

320 
eosin, 291 



INDEX. 



465 



Stains, eosin and methylene-blue, 

method, 315 
method, 316 
Exner's, for myelin-sheath, 347 
Flexner's, for leprosy bacillus, 415 
for actinomyces, 412 
for albuminous degenerations, 386 
for amoeba coli, 423 
for amyloid, 398 

for axis-cylinder processes, 334, ^^8 
for bacillus diphtherias, 162 

typhosus, 408 
for bacteria in tissue, 405 
for blood, 369 
for blood-films, 372 
for bone, 380 
for calcification, 404 
for cartilage, 380 
for caseation, 389 
for cellulose, 400 
for central nervous system, 329. See 

also Central nervous system. 
for chancroid bacillus, 410 
for cholesterin crystals, ^88, 4°° 
for cloudy swelling, 386 
for colloid, 393 

for connective-tissue fibrillse, 322 
for corpora amylacea, 400 
for cover-glass preparations, 92, 94 

from cultures, 10 1 

Gram's, 94 

bacteria decolorized by, 95 
stained by, 95 

Pappenheim's pyronin and 
methyl-green mixture, 94 

simple, 94 
for degenerations of nervous system, 

353 . 

for dendritic processes, 334 
for elastic fibers, 326 
for fat, 386 

for fat-acid crystals, t>88 
for fatty degeneration of myelin- 
sheath, 354 

of nerve-fibers, 354 
for ferric salts, 404 
for ferrous salts, 404 
for fibrin, 389 
for fibroglia fibrils, 324 
for flagella, 102. See also Flagella, 

staining of. 
for fresh tissue, 252 
for Friedlander's capsule- bacillus, 

410 
for ganglion-cells, 334 
for glanders bacillus, 409 
for glycogen, 396 
for gonococci, 148, 150, 408 
for hyalin, 393 

30 



Stains for influenza bacillus, 408 
for iron in hemosiderin, 403 

Stieda's method for permanent 
mounts, 404 
for karyomitosis, 318 
for Loffier's bacillus, 162 
for mastzellen, 320 
for mitosis, 318 
for mucin, 391 
for myelin-sheath, 342 
for necrosis, ^88 
for nerve-fibers, ^^8 
for neuroglia-fibers, 348 
for Nissl, 233 
for petrifaction, 404 
for plasma-cells, 321 
for pneumococcus capsule, 142 
for reticulum, 322 
for rhinoscleroma bacillus, 411 
for skin, 382 

parasites, ^8^ 
for smegma bacillus, 416 
for smooth muscle-cells, 328 
for spores, 10 1 

Abbott's, 1 01 

Moeller's, 101 
for starch-granules, 400 
for striated muscle-cells, 328 
for syphilis bacillus, 416 
for terminal processes, 338 
for tigroid bodies, ^^^ 
for tubercle bacillus, 413 

in celloidin sections, 414 
formic-acid, 303 

Freund's gold, for nerve-fibers, 339 
fuchsin, 289 

Gabbet's methylene-blue, 288 
gentian-violet, 289 

for amyloid, 400, 401 

for glycogen, Lubarsch's, 397 
Gerlach's gold, for nerve-fibers, 339 
Giacomi's, for syphilis bacillus, 416 
glycerin-alum-hematein, Mayer's, 

2S3 
gold as, 302 

for nerve-fibers, 338 
Golgi's corrosive-sublimate method, 
Cox's modification, 338 
for nervous tissue, 334-337 

Kallius' fixing method, 33S 
Gram's, 410 

bacteria not stained by, 407 
bacteria stained by, 410 
Gram-Weigert, for bacteria, 411 
Heidenhain's hematoxylin, 310, 311 

iron hematoxylin, method, 31 1 
Heller's, for myelin-sheath, 347 

Robertson's modification, 348 
hemalum, acid, Mayer's, 2S3 



460 



IXDEX. 



Stains, hemalum, Mayer's 283 
method, 310 
hematein, 280 

glycerin-alum-, Mayer's, 283 
hematoxylin, 280 
acid, Ehrlich's, 282 
method, 309 
phosphomolybdic, 2S4 
phosphotungstic, 284 
alcohol, Weigert's, 284 
alum, 280, 281 
method, 308 
alum aqueous, method, 309 
chlorid of iron, Mallory's, method, 

311 
Delafield's, 282 

method, 309 
Heidenhain's, 310, 31 1 
iodin-, Lubarsch's, for glycogen, 

.397 , 

iron, Heidenhain's, method, 31 1 
phosphomolybdic acid, 284 
phosphotungstic acid, for neurog- 

lia-fibers, 352 
Weigert's alcohol, 284 
Hoyer's thionin for mucin, 392 
iodin, 296 

and sulphuric-acid, for amyloid, 
400 
for cellulose, 400 
for chdlesterin crystals, 400 
for corpora amylacea, 400 
for starch granules, 400 
for amyloid, 399 
for glycogen, 397 
Langhans', for glycogen, 397 
iodin-green, for amyloid, 400 
iodin-hematoxylin, Lubarsch's, for 

glycogen, 397 
iron-alizarin-toluidin-blue, for neur- 
oglia fibrils, 353 
Kallius' fixing method for Golgi's,337 
Kuhne's, for tubercle bacillus, 414 

methylene-blue, 288 
Langhans', for permanent mounts of 
amyloid, 399 
iodin, for glycogen, 397 
Leischman's, for blood, 370 
Lenhossek's, for tigroid bodies, 334 
lithium carmine, 31 1 

Orth's, 286 
Loffler's methylene-blue, 288 
for bacteria, 407 
for glanders bacillus, 409 
Lowit's formic acid, 303 
Lubarsch's gentian-violet, for glyco- 
gen, 307 
iodin-hematoxylin, for glycogen, 
397 



Stains, Lugol's solution, 296 

Lustgarten's, for syphilis bacillus, 

416 
Mallory's, for actinomyces, 412 
aniline-blue, for connective-tissue. 

322 
chlorid of iron hematoxylin, 

method, 311 
for fibroglia fibrils, 325, 329 
for neuroglia-fibers, 349 
Mall's, for reticulum, 324 
Marchi's, for fatty degeneration of 

nervous tissue, 354 
Mayer's carmine, alcoholic, 286 
for amyloid, 401 
glycerin-alum-hematein solution, 

283 
hemalum, 283 
acid, 283 
method, 310 
muchematein, 283 
metallic, 301. See also Metallic 

stains. 
methylene-blue, 287 
and eosin, method, 315 
for nerve-fibers, 340 
Loffler's, for bacteria, 407 

for glanders bacillus, 409 
Unna's polychrome, for mucin, 
392 
methyl-violet, 290 
for amyloid, 400 
Morris', for skin parasites, 383 
muchematein, Mayer's, 283 
nigrosin, for nervous system, 333 
Nissl's, 333 
nitrate of silver, 301 
Noniewicz's, for glanders bacillus, 

409 
nuclear, 308. See also Nuclear 

stains. 
orcein, 296 

Orth's lithium carmine, 286 
osmic acid, 303 
osmium, for fat, 387 

tetroxid, 303 
Pal's modification of ^Yeigert's, for 

myeiin-sheath, 345 
paracarmine, 286 
perosmic acid, 303 
phosphomolvbdic acid hematoxvlin, 
2S4 ' 
for nervous system, 332 
phosphotungstic acid hematoxvlin, 
284 
for nervous system, 332 
for neuroglia-fibers, 352 
Pianese's, 293 
picric acid, 291 



INDEX. 



467 



Stains, picric acid, method, 316 
picrofuchsin, van Gieson"s, 291 
picro-nigrosin, 292 
Ranvier's formic acid, 303 
Robertson's modification of Heller's, 

for myelin-sheath, 348 
Romanowsky's, for malarial organ- 
isms, 370, 371, 421 
safranin, 290 

for karyomitotic figures, 319 
Schaffer's, for differentiating bone 
from cartilage, 380 
Sahli's borax methylene-blue, 289 
Schaffer's safranin, for differentiating 

bone from cartilage, 380 
Scharlach R., for fat, 387 

for fresh tissue, 254 
Schmorl's, for differentiating bone 

from cartilage, 380 
Schultz's, for glanders bacillus, 409 
silver, 301 
special, 320 

Stirling's gentian-violet, 289 
Stroebe's aniline blue, for nerve- 
fibers, 339 
Sudan III, for fat, 387 
for fresh tissue, 254 
thionin, Hoyer's, for mucin, 392 
tubercle bacillus method, bacteria 

stained by, 413 
Unna's, for colloid, 395 
for connective tissue, 323 
for elastic fibers, 327 
for hyalin, 395 
for mastzellen, 321 
for plasma-cells, 321 
methylene-blue, alkaline, 288 
polychrome, 288 
for mucin, 392 
polychrome methylene-blue, 392 
van Gieson's diffuse, method, 316 
for connective-tissue, 323 
for nervous system, 331 
picro-fuchsin, 291 
Weigert's alcohol hematoxylin, 284 
for fibrin, 390 
for myelin-sheath, 343 

Pal's modification, 345 
for neuroglia-fibers, 350 
Wei gert- Gram, for bacteria, 411 
Wright's, for blood, 370 

for blood-films, microscopic ap- 
pearances, 374 
for malarial parastes, 421 
Ziehl-Neelson's carbol-fuchsin, 289 
Ziehl-Neelson-Gabbet, for tubercle 
bacillus, 414 
Staphylococcus cereus albus, 134 
flavus, 134 



Staphylococcus epidermidis albus, 134 
pyogenes albus, 134 
aureus, 131 

diagnosis, 133 
citreus, 134 

gonococcus and, differentiation, 
148 
Starch-granules, iodin and sulphuric 

acid for, 400 
Stearin, 386 
Stender dishes, 251 
Stepanow's celloidm imbedding, 272 
Sterilization of culture-media, 87 

autoclave for, 88 
Sternberg's modification of Esmarch's 
roll-culture method, 112 
sputum-septicemia, 140 
Stieda's method for permanent mounts 

of hemosiderin, 404 
Stirling's gentian-violet, 289 
Stomach, 378 

contents, 446. See also Gastric 

contents. 
hemorrhage from, autopsy guides, 23 
opening of, 43 
removal of, 42 
Streptococcus brevis, 136 
capsulatus, 143 
conglomeratus, 136 
eiysipelatus, 135 
longus, 1 36 
pyogenes, 134 
diagnosis, 138 
gonococcus and, differentiation, 

148 
pneumococcus and, differentiation, 

135 

Striated muscle-cells, staining, 328 
Stroebe's aniline blue for nerve-fibers, 

.339 
Stropping, 248, 249 
Subcutaneous inoculation of guinea- 

pigs, 116 
Sudan III for fat, 387 
for fresh (issue, 254 
Sudden death, autopsy guides, 24 

opening heart in, 35 
Sulphuric acid and iodin for amyloid, 
400 
for cellulose, 400 
for cholesterin crystals, 400 
for corpora amylacea, 400 
for starch-granules, 400 
Sulphurous acid in decalcification, 269 
Surgical tuberculosis, 186 
Suspension, 120 
Swabs, qo 

Syphilis bacillus, Giacomi's method 
for, 416 



468 



INDEX. 



Syphilis bacillus, Lustgarten's method 
for, 416 
staining, 416 
Syracuse solid watch-glasses, 250 

T^NIA ECHINOCOCCUS, 429 

mediocanellata solium saginata, 428 

solium, 427 
Tape-worms, 427 
Tea infuser, Hobb's, 251 
Teased preparations, 252 
Tellyesniczky's mixture as fixative, 267 
Terminal infection, 137 

processes, stains for, 338 
Tertian parasite, 417 

cycle of, 416 
Testicles, removal of, 48 

weight of, 48 
Test-tubes, filling, 85 

preparation of, for cultures, 70 

quantity of medium in, 86 
Tetanus bacillus, 219 

toxin of, 222 
Thionin, Hover's, for mucin, 392 
Thoma-Zeiss hemocytometer, 355 
Thoracic duct, position of, 49 

organs, removal of, 37 
Thorax, incision to bare, 28, 30 

opening of, 28, 30 
Thyme, oil of, as clearing reagent, 299 
and cloves, as clearing reagent, 
299 
Tigroid bodies, stains for, 2>2>1> 
Tincture of iodin as stain, 296 
Tissue, fresh. See Fresh tissue. 

from clinical cases, examination for 
diagnosis, 430 
Tissue-elements, those stained, 305 
Titration in adjustment of media reac- 
tion, 83 
Topfer's dimethyl - amido-azo - benzol 

test for hydrochloric acid, 447 
Toxalbumin of bacillus diphtherias, 160 

tetanus, 222 
Toxin, bacillus diphtheriae, 160 

tetanus, 222 
Transplanting culture, 107 
Transudations, examination, 431 
Trichinae, 426 
Trichloracetic acid in decalcification, 

269 
Tubercle bacillus, 180. See also 

Bacillus tuberculosis. 
Tubercles, glanders, 211 
Tuberculosis, autopsy guides, 23 

bacillus of, 180. See also Bacillus 
tuberculosis. 

surgical, 186 
Twine, hemp, 21 



Typhoid fever, bacillus of, 163. See 
also Bacillus typhosus. 

Umbilical arteries, examination, 65 

cord, examination, 65 
Unna's method for mastzellen, 321 
methylene-blue, alkaline, 288 

polychrome, 288, 392 
orcein for connective tissue, 323 

for elastic fibers, 327 
polychrome methylene-blue for 

mucin, 392 
stain for colloid, 395 

for connective tissue, 323 
for hyalin, 395 
for plasma-cells, 321 
Urinary tract, removal of, 46 
Urine, bacillus tuberculosis in, 186 

examination of, 448 
Uterine scrapings, examination, 430 
Uterus, opening of, 48 

Vacuo, anaerobes in, 130 

Vagina, incision of, 48 

Valvular competence, water-test for, 

35 
Van Gieson's connective-tissue stain, 

323 

diffuse stain, method, 316 

nervous tissue stain, 331 

picro-fuchsin, 291 
Vegetable parasites in sputum, 445 
Vena cava, inferior, opening of, 49 
Ventricles, opening of, 34 
Vertebral column, removal of, 50 
Vibrio, cholera, 188. See also Comma 

bacillus. 
Virchow's method for examining brain, 

58 
Von Drigalski-Conradi's medium for 

bacillus typhosus 171 
Von Fleischl's hemometer, 357 
Vulcanized fiber for mounting, 247 

Watch-glasses, Syracuse solid, 250 
Water, bacillus coli communis in, 176 
running, for washing specimens, 249 
Water-test of valvular competence, 35 
Wedge-shaped incision for opening 

skull, 51 
Weigert's alcohol hematoxylin, 284 
differential stain for fibrin, 390 
method for serial celloidin sections, 

278 
mixtures as clearing reagents, 299, 

300 
stain for elastic fibers, 326 
for myelin-sheath, 343 
Pal's modification, 345 



INDEX. 



469 



Weigert's stain for neuroglia-fibers, 

350 
W eigert-Gram method for bacteria, 

411 
\\ elch's method for staining capsule 

of pneumococcus, 142 
White corpuscles. See Leucocytes. 

blood-globules in sputum, 444 
Widal's method for examination of 

serous fluids, 432, 433 
reaction, 167, 168 
William's method for staining flagella, 

\\ ool-sorters' disease, bacillus of, 195 

diagnosis, 198 
Worms, round-, 425 

tape-, 427 
Wounds inflicted at autopsy, treat- 
ment, 23 
Wright's fluid for frozen sections, 263 



Wr'ght's imbedding method for frozen 
sections, 279 
method for anaerobes, 125 

in fluid media, 126 
stain for blood, 370 

for blood-films, microscopic ap- 
pearances after, 374 
for malarial parasites, 421 

Xylol and aniline as clearing reagent, 

300 
and carbolic acid as clearing reagent, 

299 
as clearing reagent, 299 
balsam, 300 

Ziehl-Neei.SON's carbol-fuchsin, 289 
Ziehl-Neelson-Gabbet method for 

tubercle bacillus, 414 
Zenker's fluid as fixative, 258, 259 



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in the Histologic and Chemic Examination of Drugs. By Robert A. 
Hatcher, Ph. G m M. D., of Cornell University Medical School, New 
York City ; and Torald Sollmann, M.D., of the Western Reserve Uni- 
versity, Cleveland, Ohio. i2mo of about 300 pages. Flexible leather. 

JUST ISSUED— FOR PHARMACY STUDENTS 

This work is a practical text-book, treating the subject by actual experimental 
demonstrations. Part I. comprises a guide. to the study of crude drugs, both 
official and unofficial. In Parts II. and III. the histologic and chemic examina- 
tions of drugs are considered in a scientific, yet clear and simple manner. 

Eichhorst's Practice 

A Text=Book of the Practice of Medicine. By Dr. Hermann 
Eichhorst, University of Zurich. Translated and edited by Augus- 
tus A. Eshner, M.D., Professor of Clinical Medicine, Philadelphia 
Polyclinic. Two octavos of 600 pages each, with over 150 illustra- 
tions. Per set : Cloth, $6.00 net ; Sheep or Half Morocco, $7.50 net. 

Bulletin of Johns Hopkins Hospital 

"This book is an excellent one of its kind. Its completeness, yet brevity, the clinical 
methods, the excellent paragraphs on treatment and watering-places, will make it very 
desirable." 

Bridge on Tuberculosis 

Tuberculosis. By Norman Bridge, A.M., M.D., Emeritus Pro- 
fessor of Medicine in Rush Medical College, in affiliation with the 
University of Chicago. i2mo of 302 pages, illustrated. Cloth. 
$1.50 net. 

Medical News, New York 

" Thoroughly representative of our practical methods of diagnosis and treatment of the 
disease." 



SAUNDERS' BOOKS ON 



Rolleston on the Liver 



Diseases of the Liver. By Humphrey D. Rolleston, M. D., 
F. R. C. P., Physician to St. George's Hospital, London, England. 
Octavo volume of about 850 pages, with beautiful illustrations, in- 
cluding a number in colors. 

ENTIRELY NEW— JUST ISSUED 

This work covers the entire field of diseases of the liver, and is the most 
voluminous work on this subject in English. Dr. Rolleston has for many years 
past devoted his time exclusively to diseases of the digestive organs, and any- 
thing from his pen, therefore, is authoritative and practical. Special attention is 
given to pathology and treatment, the former being most profusely illustrated 
both with pictures of the gross appearances and with microphotographs. There 
are also a number of exceptionally beautiful and accurate colored plates. Dr. 
Rolleston' s work will become the authority on diseases of the liver. 



Boston's 
Clinical Diagnosis 



Clinical Diagnosis. By L. Napoleon Boston, M. D., Demonstra- 
tor in Charge of Clinical Laboratory, Medico-Chirurgical College, 
Philadelphia. Octavo of 525 pages, with 200 illustrations, including 
25 colored plates. 

A NEW WORK— JUST ISSUED 

The clinical examination of sputum, feces, blood, etc. has assumed such an im- 
portant place in practice that a thorough knowledge of the significance of chemic 
and microscopic laboratory findings becomes absolutely necessary to success- 
ful therapeusis. Dr. Boston here presents a practical manual of the clinical and 
laboratory examinations which furnish a guide to correct diagnosis, giving only 
such methods, however, which can be carried out by the busy practitioner in his 
office as well as by the student in the laboratory. The chapter on Serum Diagno- 
sis is particularly complete. 



MATERIA ME DIC A. 



GET M • THE NEW 

THE BEST l\ lH © r 1 C Si II STANDARD 

Illustrated Dictionary 

Third Revised Edition — Just Issued 



The American Illustrated Medical Dictionary. A new and com- 
plete dictionary of the terms used in Medicine, Surgery, Dentistry, 
Pharmacy, Chemistry, and kindred branches; with over ioo new and 
elaborate tables and many handsome illustrations. By W. A. Newman 
Dorland, M. D., Editor of " The American Pocket Medical Diction- 
ary." Large octavo, nearly 800 pages, bound in full flexible leather. 
Price, $4.50 net; with thumb index, $5.00 net. 

Gives a Maximum Amount of Matter in a Minimum Space, and at the Lowest 

Possible Cost 

THREE EDITIONS IN THREE YEARS— WITH 1500 NEW TERMS 

The immediate success of this work is due to the special features that distin- 
guish it from other books of its kind. It gives a maximum of matter in a mini- 
mum space and at the lowest possible cost. Though it is practically unabridged, 
yet by the use of thin bible paper and flexible morocco binding it is only 1 % 
inches thick. The result is a truly luxurious specimen of book-making. In this 
new edition the book has been thoroughly revised, and upward of fifteen hundred 
new terms that have appeared in recent medical literature have been added, thus 
bringing the book absolutely up to date. The book contains hundreds of terms 
not to be found in any other dictionary, over 100 original tables, and many hand- 
some illustrations, a number in colors. 



PERSONAL OPINIONS 



Howard A. Kelly, M. D., 

Professor of Gynecology, Johns Hopkins University , Baltimore. 

" Dr. Dorland's dictionary is admirable. It is so well gotten up and of such convenient 
size. No errors have been found in my use of it." 

Roswell Park, M. D., 

Professor of Principles and Practice of Surgery and of Clinical Surgery, University of 
Buffalo. 
. "I must acknowledge my astonishment at seeing how much he has condensed within rela- 
tively small space. I find nothing to criticize, very much to commend, and was interested in 
finding some of the new words which are not in other recent dictionaries." 



SAUNDERS' BOGKS ON 



Saunders' 
Pocket Medical Formulary 

Sixth Edition, Revised 



Saunders' Pocket Medical Formulary. By William M. Powell, 
M. D., author of " Essentials of Diseases of Children " ; Member of 
Philadelphia Pathological Society. Containing 1844 formulas from the 
best-known authorities. With an Appendix containing Posological 
Table, Formulas and Doses for Hypodermic Medication, Poisons 
and their Antidotes, Diameters of the Female Pelvis and Fetal Head, 
Obstetrical Table, Diet-lists, Materials and Drugs used in Antiseptic 
Surgery, Treatment of Asphyxia from Drowning, Surgical Remem- 
brancer, Tables of Incompatibles, Eruptive Fevers, etc., etc. In flex- 
ible morocco, with side index, wallet, and flap. $2.oa net. 

CONTAINING 200 NEW FORMULAS 

In compiling this handy volume the author has introduced as many of the 
more important recently discovered drugs as possible. Besides the many hun- 
dreds of famous formulas collected from the works of the most eminent physicians 
and surgeons of the world, it contains many valuable, and hitherto unpublished, 
prescriptions from the private practice of distinguished practitioners of to-day. 
In this new edition the work has been thoroughly and carefully revised and cor- 
rected, and some two hundred new and valuable formulas added. The Dose- 
table has been brought up to date, and the entire work made to comply in every 
way with the latest knowledge on the subjects it contains. 



OPINIONS OF THE MEDICAL PRESS 



Medical Record, New York 

"This little book, that can be conveniently carried in the pocket, contains an immense 
amount of material. It is very useful, and, as the name of the author of each prescription is 
given, is unusually reliable." 

Johns Hopkins Hospital Bulletin 

" Arranged in such a way as to make consultation of it as easy as possible. It is remark- 
able how much information the author has succeeded in getting into so small a book." 

Boston Medical and Surgical Journal 

" The book is attractively bound in flexible leather, and the fact that it has reached its 
sixth edition bears ample testimony to its popularity." 



MATERIA MEDICA AND THERAPEUTICS. 

Stevens' Materia Medica 
and Therapeutics 



A Text=Book of Modern Materia Medica and Therapeutics. By 

A. A. Stevens, A. M., M. D., Lecturer on Physical Diagnosis in the 
University of Pennsylvania. Handsome octavo volume of 663 pages, 
Cloth, $3.50 net. 

JUST ISSUED— THIRD EDITION, REWRITTEN AND ENLARGED 

Since the appearance of the last edition of this book such rapid advances 
have been made in Materia Medica, Therapeutics, and the allied sciences that 
the author felt it imperative to rewrite the work entirely. All the newer reme- 
dies that have won approval by recognized authorities have been incorporated, 
and their therapeutic properties fully discussed, thus bringing the book absolutely 
down to date. The work includes the following sections : Physiologic Action of 
Drugs ; Drugs ; Remedial Measures other than Drugs ; Applied Therapeutics ; 
Incompatibility in Prescriptions ; Table of Doses ; Index of Drugs ; and Index 
of Diseases ; the treatment being elucidated by more than two hundred formulae. 



OPINIONS OF THE MEDICAL PRESS 



University Medical Magazine 

"The author has faithfully presented modern therapeutics in a comprehensive work . . . 
and it will be found a reliable guide and sufficiently comprehensive for the physician in 
practice." 

Bristol Medico-Chirurg'ical Journal, Bristol 

"This addition to the numerous works on Therapeutics is distinctly a good one. ... It 
is to be recommended as being systematic, clear, concise, very fairly up to date, and carefully 
indexed." 



Monro's Manual of Medicine just issued 

Manual of Medicine. By Thomas Kirkpatrick Monro, M. A., M. D., 
Fellow of, and Examiner to, the Faculty of Physicians and Surgeons, 
England ; Glasgow Physician to Glasgow Royal Infirmary, Glasgow, etc 
Octavo volume of 901 pages, illustrated. Cloth, $5.00 net. 



12 SAUNDERS' BOOKS ON 

Thornton's Dose-Book 

Dose=Book and Manual of Prescription=Writing. By E. Q. Thorn- 
ton, M. D., Assistant Professor of Materia Medica, Jefferson Medical 
College, Phila. Post-octavo, 362 pages, illustrated. Flexible Leather, 
$2.00 net. 

Second Edition, Revised and Enlarged 

In the new edition of this work, intended for the student and practitioner, 
additions have been made to the chapters on "Prescription-Writing" and 
"Incompatibilities," and references have been introduced in the text to the 
newer curative sera, organic extracts, synthetic compounds, and vegetable drugs. 
To the Appendix, chapters upon Synonyms and Poisons and their antidotes 
have been added, thus increasing its value as a book of reference. 

C. H. Miller, M. D., 

Professor of Pharmacology, Northwestern University Medical School, Chicago. 

" I will be able to make considerable use of that part of its contents relating to the correct 
terminology as used in prescription-writing, and it will afford me much pleasure to recommend 
the book to my classes, who often fail to find this information in their other text-books." 



Barton and Welly' 
Medical Thesaurus 



A Thesaurus of Medical Words and Phrases. By Wilfred M. 
Barton, M. D., Assistant to Professor of Materia Medica and Thera- 
peutics, Georgetown University, Washington, D. C. ; and Walter A. 
Wells, M. D., Demonstrator of Laryngology, Georgetown University, 
Washington, D. C. i2mo of 534 pages. Flexible leather, $2.50 net ; 
with thumb index, $3.00 net. 

A UNIQUE WORK— JUST ISSUED 

This work is just the opposite of a dictionary : when the idea or meaning is 
in the mind, it endeavors to supply the term or phrase to express that idea. Its 
value is evident. 

Boston Medical and Surgical Journal 

"We can easily see the value of such a book, and can certainly recommend it to our 
readers." 



THE PRACTICE OF MEDICINE. 13 

Gould and Pyle's 
Curiosities of Medicine 



Anomalies and Curiosities of Medicine. By George M. Gould, 
M. D., and Walter L. Pyle, M. D. An encyclopedic collection of 
rare and extraordinary cases and of the most striking instances of 
abnormality in all branches of Medicine and Surgery, derived from an 
exhaustive research of medical literature from its origin to the present 
day, abstracted, classified, annotated, and indexed. Handsome octavo 
volume of 968 pages, 295 engravings, and 12 full-page plates. 

Popular Edition : Cloth, #3.00 net ; Sheep or Half Morocco, $4-00 net. 

As a complete and authoritative Book of Reference this work will be of value 
not only to members of the medical profession, but to all persons interested in 
general scientific, sociologic, and medicolegal topics ; in fact, the absence of any 
complete work upon the subject makes this volume one of the most important 
literary innovations of the day. 

The Lancet, London 

" The book is a monument of untiring energy, keen discrimination, and erudition. . . . 
We heartily recommend it to the profession." 

Saunders' Year-Book 



The American Year=Book of Medicine and Surgery. A Yearly- 
Digest of Scientific Progress and Authoritative Opinion in all branches 
of Medicine and Surgery, drawn from journals, monographs, and text- 
books of the leading American and foreign authors and investigators. 
Arranged with critical editorial comments by eminent American special- 
ists, under the editorial charge of George M. Gould, M. D. In two 
volumes — Vol. I., including General Medicine ; Vol. II., General Sur- 
gery. Per volume: Cloth, $3.00 net ; Half Morocco, $3.75 net. Sold 
by Subscription. 

EQUIVALENT TO A POSTGRADUATE COURSE 

The Lancet, London 

" It is much more than a mere compilation of abstracts, for, as each section is entrusted to 
experienced and able contributors, the reader has the advantage of certain critical commen- 
taries and expositions . . proceeding from writers fully qualified to perform these tasks." 



14 SAUNDERS' BOOKS ON 

Sollmann's Pharmacology 

Including Therapeutics, Materia Medica. Pharmacy, 
Prescription -writing', Toxicology, etc. 



A Text=Book of Pharmacology, By Torald Sollmann, M. D., 
Assistant Professor of Pharmacology and Materia Medica, Medical 
Department of Western Reserve University, Cleveland, Ohio. Hand- 
some octavo volume of 894 pages, fully illustrated. Cloth, $3.75 net. 

A NEW WORK— RECENTLY ISSUED 

This work aims to furnish a scientific discussion and definite conception of the 
action of drugs, as well as their derivation, composition, strength, and dose. The 
author bases the study of therapeutics on a systematic knowledge of the nature 
and properties of drugs, and thus brings out forcibly the intimate relation between 
pharmacology and practical medicine. 

J. F. Fotheringham, M. D. 

Prof, of Therapeutics and Theory and Practice of Prescribing, Trinity Med. College, Toronto. 
"The work certainly occupies ground not covered in so concise, useful, and scientific a 
manner by any other text I have read on the subjects embraced." 

Butler's Materia Medica 

Therapeutics, and Pharmacology 

A Text=Bookof Materia Medica, Therapeutics, and Pharmacology. 

By George F. Butler, Ph. G., M. D., Professor of Materia Medica and 
of Clinical Medicine, College of Physicians and Surgeons, Chicago, 
Octavo, 896 pages, illustrated. Cloth, $4.00 net ; Sheep or Half Morocco, 
$5.00 net. 

FOURTH EDITION, REVISED AND ENLARGED 

In this new edition the chapters on Organo-therapy, Serum-therapy, and cog- 
nate subjects have been enlarged and carefully revised. An important addition 
is the chapter devoted to the newer theories of electrolytic dissociation and its 
relation to the topic of pharmacotherapy. 

Medical Record, New York 

" Nothing has been omitted by the author which, in his judgment, would add to the com- 
pleteness of the text, and the student or general reader is given the benefit of latest advices 
bearing upon the value of drugs and remedies considered." 



PRACTICE, MATERIA MEDIC A, Etc. 15 

The American Pocket Medical Dictionary. 4th Edition, just Ready 

The American Pocket Medical Dictionary. Edited by W. A. Newman Dor- 
land, M. D., Assistant Obstetrician to the Hospital of the University of Pennsylvania. 
Containing the pronunciation and definition of the principal words used in medicine 
and kindred sciences, with 64 extensive tables. Flexible leather, with gold edges, 
#1.00 net; with thumb index, $1.25 net. 

" I can recommend it to our students without reserve." — J. H. Holland, M. D., Dean of the 
Jefferson Medical College, Philadelphia. 

Vierordt's Medical Diagnosis. Fourth Edition, Revised 

Medical Diagnosis. By Dr Oswald Vierordt, Professor of Medicine, Univer- 
sity of Heidelberg. Translated from the fifth enlarged German edition by Francis 
H. Stuart, A. M., M. D. Octavo, 603 pages, 104 wood cuts. Cloth, $4. 00 net; 
Sheep or Half Morocco, $5.00 net. 

" Has been recognized as a practical work of the highest value. It may be considered indispensable 
both to students and practitioners." — F. Minot, M. D., late Professor of Theory and Practice in 
Harvard University. 

Cohen and Eshner's Diagnosis. Second Revised Edition 

Essentials of Diagnosis. By S. Solis-Cohen, M. D., Senior Assistant Professor 
in Clinical Medicine, Jefferson Medical College, Phila. ; and A. A. Eshner, M. D., 
Professor of Clinical Medicine, Philadelphia Polyclinic. Post-octavo, 382 pages ; 55 
illustrations. Cloth, $1. 00 net. In Saunders 1 Question- Compend Series. 

" Concise in the treatment of subject, terse in expression of fact." — American Journal of the 
Medical Sciences. 

Just Issued 

Morris' Materia Medica and Therapeutics, sixth Revised Edition 

Essentials of Materia Medica, Therapeutics, and Prescription-Writing. 
By Henry Morris, M. D., late Demonstrator of Therapeutics, Jefferson Medical 
College, Phila. Post-octavo, 250 pages. Cloth, $i.co net. In Saunders 1 Question- 
Compend Series. 

" Cannot fail to impress the mind and instinct in a lasting manner." — Buffalo Medical Journal. 

Sayre's Practice of Pharmacy. Second Edition, Revised 

Essentials of the Practice of Pharmacy. By Lucius E. Sayre, M. D., Pro- 
fessor of Pharmacy, University of Kansas. Post-octavo, 200 pages. Cloth, $1.00 net. 
In Saunders' Question- Compend Series. 

" The topics are treated in a simple, practical manner, and the work forms a very useful student's 
manual." — Boston Medical and Surgical Journal. 

Brockway's Medical Physics. Second Edition, Revised 

Essentials of Medical Physics. By Fred. J. Brockway, M. D., late Assistant 
Demonstrator of Anatomy, College of Physicians and Surgeons, N. Y. Post-octavo, 
330 pages; 155 fine illustrations. Cloth, $1.00 net. In Saunders' Question- Compend 
Series. 

" It contains all that one need know on the subject, is well written, and is copiously illustrated." — 
Medical Record, New York. 

Stoney's Materia Medica for Nurses SecoJteSldi*,,. 

Materia Medica for Nurses. By Emily A. M. Stoney, Superintendent of the 
Training School for Nurses at the Carney Hospital, South Boston, Mass. Handsome 
i2mo volume of 300 pages. Cloth, $1.50 net. 

"It contains about everything that a nurse ought to know in regard to drugs." — Journal of the 
American Medical Association. 

Grafstrom's Mechanotherapy Second^Xtl^ed 

A Text-Book of Mechano-therafy (Massage and Medical Gymnastics). By 
Axel V. Grafstrom, B. Sc, M. D., Attending Physician to Augustus Adolphus Orphan- 
age, Jamestown, N. Y. 121110, 200 pages, illustrated. $1.25 net. 

"Certainly fulfills its mission in rendering- comprehensible the subjects of massage and medica! 
gymnastics." — New Yo>-k Medical Journal. 



1 6 SAUNDERS' BOOKS ON PRACTICE, Etc. 

Jakob and Eshner's Internal Medicine and Diagnosis 

Atlas and Epitome of Internal Medicine and Clinical Diagnosis. By Dr. 
Chr. Jakob, of Erlangen. Edited, with additions, by A. A. Eshner, M. D., Pro- 
fessor of Clinical Medicine, Philadelphia Polyclinic. With 182 colored figures on 
68 plates, 64 text-illustrations, 259 pages of text. Cloth, $3.00 net. In Saunders' 
Hand- Atlas Series. 

" Can be recommended unhesitatingly to the practicing physician no less than to the student." — 
Bulletin of Johns Hopkins Hospital. 

Lockwood's Practice of Medicine. tJSSdtdS^i 

A Manual of the Practice of Medicine. By Geo. Roe Lockwood, M. D., 
Attending Physician to the Bellevue Hospital, New York City. Octavo, 847 pages, 
with 79 illustrations in the text and 22 full-page plates. Cloth, $4.00 net. 

" A work of positive merit, and one which we gladly welcome." — New York Medical Journal. 

Salinger and Kalteyer's Modern Medicine 

Modern Medicine. By Julius L. Salinger, M. D., late Ass't Prof, of Clinical 
Medicine, Jefferson Medical College; and F. J. Kalteyer, M. D., Demonstrator of 
Clinical Medicine, Jefferson Medical College. Handsome octavo, 801 pages, illus- 
trated. Cloth, $4.00 net. 

" I have carefully examined the book, and find it to be thoroughly trustworthy in all respects and a 
valuable text-book for the medical student." — Sam'l O. L. Potter, Formerly Professor of Principles 
and Practice of Medicine, Cooper Medical College, San Francisco. 

Heating's Life Insurance 

How to Examine for Life Insurance. By the late John M. Keating, M. D., 
Ex-President of the Association of Life Insurance Medical Directors. Royal octavo, 
211 pages. With numerous illustrations. Cloth, $2.00 net. 

" This is by far the most useful book which has yet appeared on insurance examination." — Medical 
News. 

Corwin's Physical Diagnosis. Third Edition, Revised 

Essentials of Physical Diagnosis of the Thorax. By A. M. Corwin, A. M., 
M. D., Professor of Physical Diagnosis, College of Physicians and Surgeons, Chicago. 
220 pages, illustrated. Cloth, flexible covers, $1.25 net. 

" A most excellent little work. It arranges orderly and in sequence the various objective phenomena 
to logical solution of a careful diagnosis. "—Journal of Nervous and Mental Diseases. 

American Text-Book of Theory and Practice 

American Text-Book of the Theory and Practice of Medicine. Edited 
by the late William Pepper, M. D., LL. D., Professor of the Theory and Practice 
of Medicine and of Clinical Medicine, University of Penna. Two handsome imperial 
octavos of about 1000 pages each. Illustrated. 'Per volume : Cloth, $5.00 net ; Sheep 
or Half Morocco, $6.00 net. 

" I am quite sure it will command itself both to practitioners and students of medicine, and become 
one of our most popular text-books."— Alfred Loomis, M. D., LL. D., Professor of Pathology and 
Practice of Medicine, University of the City of New York. 

Stevens' Practice Of Medicine. Sixth Edition, Revised— Just Issued 

A Manual of the Practice of Medicine. By A. A. Stevens, A. M., M. D., 
Lecturer on Physical Diagnosis, University of Pennsylvania. Specially intended for 
students preparing for graduation and hospital examinations. Post-octavo, 556 pages ; 
illustrated. Flexible leather, 52.25 net. 

" An excellent condensation of the essentials of medical practice for the student, and may be found 
also an excellent reminder for the busy physician." — Buffalo Medical Journal. 



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